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Thb year 1908 was one of experiments ia aerial 
navigation ; 1909 is the year of the most brilliant 

In 1908 the magnificent experiments of the Wright 
Brothers excited the admiration of all to a supreme 
degree ; and in the month of October of the same year 
two audadous aviators, Farman and BMriot, leaving 
their experimenting grounds, boldly set out into the 
realm of practice. On October 30 Farman accomplished 
the first '* aerial voyage," by travelling from Ch^ons to 
Bheims, passing over villages, forests, and hills ; and 
the next day Blfiriot achieved the first " cross-country " 
journey in a closed circle between Toury and Artenay, 
making two descents en rottte, and restarting under his 
own effort, without any launching apparatiu, finally 
returning to his starting-point. 

The "Conquest of the Air," commenced in 1885 by 
the first dirigible, La France, built by Colonel Benard, 
is to-day asserted in the new development — aviation. 

But now, in 1909, our human birds have excelled. 
By a remarkable flight, Bleriot, more fortunate than his 
rival Latham, who came to grief off his destination, sue. 
ceeded in crossing the Channel on July 25, thus realising 
through the atmosphere that entente cordiale made 

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Uik e^/u/|ii«0t baa been eflfoeted, to describe the principleii 
//f Um9 er/natnictioii and control of aerial ▼ o a po h, dirigible 
indUM^mt or aviation apparatus ; that is my reaaoo ftr 
writing this bo^ik* 

f tiavi^ written it as lucidly as possiUe, so that it can 
im ruarl by alL It has no pretensions to being an ** aero- 
fiauiiiMi^l encyclopflddia/' but rather an '' introduction to 
tti4» ttiuily of aeronautics/' that those who read and 
iifiiierstand it may be able to follow accordingly and 
with advantage the whole progress of the new science 









In One Volume, Crown 8to. Ulnstrated 
Priee 6t. 

Lokdok: William HmrxMAHH 

* T H E X I E ^ 











Dirigible* or aeroplanet. MiStary appKcaUoma. App 
to civil ttfe, SdmUfk appKeatioiu : exfloraHtm of% 
couniriet. The nuhtririal movemml created ^ oeho/i 
tion. What remamt to he done t Pjp. SS 






I. Flight of ''La France" over Paris (Sept. 25, 1885); 
voyage of the " B16riot ** aeroplane from Toury to 
Arteulay and back with two descents (Oct. 31, 
1908) FronHspUce 

Ia. M. Farman and his biplane on which he flew 180 kilo- 
metres (112^ miles) in 3 hours ; M. Paulhan finishing 
his morning flight of 50 kilometres (31^ miles) in 50 
minutes on his Voisin biplane viii 

II. The dirigible balloon '' R^pubUque " 10 

III. The screw-propeller of the " Ville de Paris " ; the screw- 

propeller of the " Bayard-C16ment " 22 

IV. The dirigible " Bayard-Clement " 24 

V. Screw-propeller and car of the German airship '' Par- 
seval " ; Col. Lowther, M. Capazza, M. Clement (car 
of the " Bayard-C16ment ") 32 

VI. Front part of the '' Bayard-Clement " car showing pro- 
peller shaft 36 

VII. The '' Bayard-Clement " returning to its garage (showing 

the details of the pneumatic empennage) 40 

VIII. The '' Bayard-Ciement " over the Madeleine ; the Place 
Venddme, the Madeleine (as seen from the '^ Bayard- 
Ciement") 46 

IX. The car of the dirigible '' Republique " 54 

X. The dirigible ^^Patrie" seen from below. The horizontal 
stabilisating empennage can be distinguished as well 
as the elevating rudder in front 70 

XI. The little detachable '' Zodiac " dirigible ; transporting 
a '' Zodiac " ; assembling a ^* Zodiac " ; dissembling 
a « Zodiac " car 78 

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XI !• Santot-Dumont's aeroplane winning the Deotidi prae; 
a '* Santos-Dumont " aeroplane ; a *' Santoa-Damont' 
dirigible ; an accident ; the little *' Santoa-DamoBt' 

XIII. The '' Ville-de-Paris " in ite garage 

XIV. The German dirigible ''Zeppelin*' nuuioeaTring over 

Lake Constance 

XV. The meUl skeleton of the dirigible ** Zeppelin " ; Sevm 
d' Albuquerque's rigid dirigible '' Pkz/' destroyed bj 
fire in Paris (1902) 

XVI. The Italian military dirigible manoeuvring over Btm- 
ciano ; the German dirigible ** Groas " 

XVII. M. Ader's ''Avion "; the "Avion " with wings folded; 
Wright making an aerial glide; OttoLilienthal glidiof; 

XVIII. M, Santos-Dumont's first trial (aeroplane without motor 
towed by the "Rapiere"); M. Santos-Dumont's 
floating aeroplane ; the Gastambide-Mangin mono- 
plane in full flight 

XIX. Henri Farman at the wheel of his aeroplane (the prow 

of the machine is to the right) U 

XX. Ck)nstructing an aeroplane wing (Ferber) 1! 

XXI. The Joanneton apparatus for recording the speed of 
airships; carrying 100 horse-power aviation motor 
(Antoinette) I 

XXII. Ciobron light motor; Esnault-Pelterie light motor; 
M. Kapf(6rer, M. Sabathier; bridge and eontrolling 
mechanism of " Bayard-Clement " I 

XXIII. H. Farman's aeroplane (Voisin, constructor); H. Far- 
man, M. Henri Deutsch ; £. Archdeacon, H. Far- 
man ; H. Farman winning the Deutsch prize ] 

XXI I Ia. Mr. Glenn Curtis, winner of the Gordon-Bennett Cup, 

Rheims, 1909 1 

XXIV. Wilbur Wright at the helm of his aeroplane (the two 
steering levers may be distinctly seen) ; the Wright 
aeroplane issuing from its garage at Auvours Camp 
(the prow is to the right) 1 

XXV. The Wright aeroplane flying ; the Wright aeroplane 
at the moment of launching by the drop of a weight 
falling from its " pylon " S 

XXVI. Louis Bleriot's monoplane in full flight (the Foster- 
chassis and the " Aileron " at the tip of each wing 
are plainly shown) S 




XXVIa. The B16riot aeroplane preparing to leave the French 
coast (the aviator standing on his bird^ and the 
wooden propeller and motor can be plainly seen) ; 

Bl6riot crossing the Channel^ July 28, 1909 212 

XXVII. The Esnault-Pelterie monoplane 21 6 

XXVIIa. Mr. Latham, winner of the height competition at 

Rheims, 1909 222 

XXVIII. Monoplane " Antoinette IV " ; motor and skate of the 

'' Antoinette " aeroplane 226 

XXIX. De la Hault's omithopt^re ; Ck)mu's h^licopt^re 232 

XXX. Henri Farman's voyage from Chalons to Rheims 24.4 

XXXI. The Br6guet; light h61icopt^re (the propellers) ; light 

h^licopt^re (motor and steering) 264 

XXXII. Chalais-Meudon Park; the Eiffel Tower; the Place 

Vend6me 266 



no. PAGE 

1 Resistance of the air upon a normally moving surface 15 

2 Influence of the front shape 15 

3 Different shapes of dirigibles 1 7 

4 Eddying action resulting from flat shape of stem 17 

5 Triangular connection suspension (indeformable) 25 

6 Air-ballonnet 27 

7 Action of the elevating rudder 31 

8 Route sUbility 38 

9 Longitudinal stability 33 

10 Instability produced by parallel connections 35 

1 1 Deformation of shape of transverse section 35 

12 Action of the ballonnet 36 

13 Imperfect equilibrium 37 

14 Cruciform empennage of the Palrie and Reptiblique 40 

15 Pneumatic empennages ^ 

16 Application point of the propelling force 43 

17 Rational arrangement of the screw 44 


no. PACK 

18 Compass card 47 

19 Example of relative wind 50 

20 Combined efiects of wind and independent speed 53 

21 Instance where the independent speed is less than the 

wind 53 

22 Case where the independent speed equals the wind 54 

23 The balloon speed is greater than the wind, so it can go 

an3rwhere 54 

24 The dirigible balloon Bayard'CUmenl 63 

25 Constructor Surcours method of '^ mooring " a dirigible 73 

26 Voyage of the BmfardClimefU (November 19O8) (iSO kilo- 

metres in a closed circle in 6ve hours^ without descent) 76 

27 A little Z<N/tac dirigible 78 

28 Design for the first dirigible by General Meusnier (1784) %5 

29 Henry Giflfard's steam driven balloon (1852) 87 

30 Captains Renard and Krebs' balloon La France (1884) 91 

31 The first two aerial voyages in a closed circle made by 

La France over Paris in 1885 93 

32 Route and altitude map of Santos-Dumont's journey (the 

Deutsch prize, October 1901) 95 

33 The dirigible balloon Lehaudy (side elevation) 97 

34 The dirigible balloon Lehaudy (under-side plan) 97 

35 The dirigible ViUe-de-ParU, offered by M. Henry Deutsch to 

the French Minister of War 101 

36 Journey of the yille-de-Paris from Sartrouville to Verdun 

(January 15, 19O8) 103 

37 The German dirigible Zeppelin 105 

38 Voyage of the Zeppelin August 4 and 5, 19O8 (606 kilometres, 

ending in the destruction of the idrship) 107 

39 Voyage of Zeppelin IIL in a closed circle (April 1909) 109 

40 The German dirigible Parseval 109 

41 The dirigible Belgique, with two propellers and twin screws 111 

42 Equilibrium of the kite 125 

43 Equilibrium of the theoretical aeroplane 128 

44 Resistance of the air upon a slanting surface 1 30 

45 Influence of the angle of attack 1 30 


no. PAGE 

46 Flat surface advancing normally through the air (the air 

molecules gliding symmetrically round the ends) 181 

47 The surface advancing obliquely through the air (the gaseous 

molecules gliding past in a dissymmetrical maunei") 131 

48 Equilibrium of the actual aeroplane 13^ 

49 Action of the empennage 133 

50 Action of a vertical '' fringe " at the stern 133 

51 A long and narrow surface 136 

52 A short and wide surface 1 36 

53 Spread of a bird's wings 1 37 

54 Evolution of the cellular^ from the multiple^ kite 141 

55 An aeroplane turning 143 

56 Principle of warping the planes (Wilbur and Orville Wright) 145 

57 The correcting ailerons (Bl^riot) 147 

58 Partitioning (MM. Voisin) 147 

59 The steering rudder 151 

60 Pisciform section of the wings 159 

61 Propulsion of an aeroplane by two screws (A^ with the two 

propellers — B^ with one only) l65 

62 Combined action of wind and propulsion speeds 171 

63 Wind and the aeroplane : actual and relative routes respec- 

tively 172 

64 Effect of inequalities of the ground surface upon the move- 

ment of the air 174 

65 Principle of the L^ger h^licopt^re 1 82 

66 Side elevation of the Capazza lenticular balloon ] 84 

67 Front view of the lenticular balloon 184 

68 Plan of Capazza's lenticular balloon 185 

69 The Voisin aeroplane (H. Farman's type) 189 

70 The Voisin aeroplane (Delagrange type) 191 

71 The W^right Brothers' aeroplane 193 

72 Details of the wing- warping action in the Wright aeroplane 197 

73 Maurice Farman's aeroplane 203 

74 L. B16riot's monoplane 209 

75 The rolling chassis of the Bl^riot aeroplane 211 

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experiment the poeaibility of steering balloons, a possi- 
bility which was triumphantly realised by Colonel 
Henard twenty-five years ago, in 1884. 

It is now therefore possible to direct a balloon floating 
in the air by virtue of the principle formulated by 
Archimedes, because its weight is less than that of the 
air it displacea This first solution of aerial navigation 
has the merit of complete novelty ; Nature has nothing 
comparable to show us; it difiers as much from the 
flight of birds as the action of a railway-train fi:om that 
of the most agile of our quadrupeds. 

But the example of birds was always present, inciting 
the human brain to seek a further solution ; the prob- 
lem was to rise into the air mechanically, without the 
cumbersome intermediary of a volume of light gas en- 
closed in an impermeable envelope ; in a word, to 
navigate the air after the manner of birds with an 
apparatus heavier than air. 

The first essays were made a long time ago, but it 
WM not until 1895 that the solution already presaged 
began to be tangible. Now at last aerial navigation 
without an aerostat, mechanical sustentation, aviation^ 
in short, is an accomplished fact ; its practical application 
is merely a question of minor improvements. 

There are then two quite distinct forms of aerial 
navigation, that of the dirigible balloon, and that of 
aviation. We have therefore a natural division for 
this book, in the first part of which we shall deal with 
dirigible balloons. 










A DIRIGIBLE balloon is an apparatus which is supported 
in the air by making use of the pressure exercised by 
this on all bodies plunged into it ; thanks to a propeller 
revolved by a motors it can and must move in this 
element at the will of the aeronaut. 

I may state the fundamental principle of aerostation 
in a very few words. 

Archimedes discovered it, and formulated it as follows : 

Every body plunged into a fluid is subjected by this 
fluid to a ^^ pressure ^^ from below to above, which is equal 
to the weight of the fluid displaced by the body. 

It is in virtue of this principle that ships float on the 

water and fish swim in it. When a body, the exterior 

volume of which is a cubic metre, is plunged into water, 

this body also displaces a cubic metre of water, or, in 

other words, 1000 litres. Now 1000 litres of water 

weigh 1000 kilogrammes. Three possibilities may then 

arise : the weight of the body immersed may be less than 

1000 kilogrammes, and it will then rise and float on 

the surface ; or it may be exactly 1000 kilogrammes, in 



which case it wiU remain in equilibrium in the water at 
a certain level; or, finally, it may weigh more than 
1000 kilogrammes,, and then it will sink to the bottom. 

These three factors are realised by fish, which are able 
at will to rise to the surface, to suspend themselves in 
the water, and to go down to the bottom ; to carry out 
these operations they vary their specific gravity by the 
help of their natatory gland, a bag containing air which 
they can dilate or compress as they please; we shall 
find later, in dealing with dirigible balloons, a similar 
organ in the " air-ballonnet." 


The principle being laid down, we may make use of it 
to raise an object into the atmosphere ; we have only to 
produce a body, the total weight of which shall be less 
than that of the volume of air it displaces. 

Now the weight of the air is known : a cubic metre of 
it weighs 1*293 kilogrammes, that is to say, about 1300 
grammes, when the temperature is at zero and the 
barometer indicates 760 millimetres. On the other hand, 
there are ^* light " gases, such as the gas used for illumi- 
nating purposes and hydrogen. A cubic metre of lighting 
gas, at zero, weighs about 500 grammes, and a cubic 
metre of hydrogen, under the same conditions, weighs 
only 110 grammes. 

Let us take this latter, the most suitable for the object 
we have in view. Let us make a huge receptacle of some 
supple and impermeable material — a " balloon " — ^and let 
us fill this " envelope " with hydrogen gas. Let us sup- 
pose that the interior volume of this receptacle is 1000 



cubic metres ; when filled with hydrogen it will weigh 
110 kilogrammes ; but the 1000 cubic metres of air that 
it displaces will weigh 1293 kilogrammes. 

The difference, i.e.^ 1183 kilogrammes, will be the 
Yeirticel pressure from below to above on the receptacle 
by virtue of Archimedes' principle. The envelope thus 
inflated with hydrogen would therefore be capable of 
lifting 1183 kilogrammes, that is to say, 1 kilogramme 
183 grammes per cubic metra. A balloon thus con- 
structed is called an aerostcU. The point where the 
pressure which supports it is exerted is called the 
centre of pressure^ and its position coincides more or less 
with that of the centre of gravity of the inflated envelope. 

If, then, the weight of the envelope itself, plus the 
weight of a support affixed to it to carry the motor and 
propeller, and the weight of the travellers, does not 
exceed 1180 kilogrammes, the apparatus will rise ; the 
difference will be its ascensional effort. If the total 
weight of the envelope and of the system it supports 
exceeds 1180 kilogrammes, the apparatus will remain 
fixed to the ground. 

If, instead of inflating our envelope with hydrogen, 
we had used lighting gas, it would only have been able 
to raise 690 kilogrammes instead of 1180; obviously 
therefore, there is an advantage in using hydrogen. 

The very existence of the ascensional efibrt produced 
by the pressure of the ambient air provides the aeronaut 
with the simple means of making his balloon rise or sink 
at wilL If he wishes to rise, he has only to throw out 
of his car a portion of the weight it contains ; ballast^ 
in the form of bags of sand, is always carried for this 
purpose. If, on the other hand, he wishes to descend. 


ting these, gives a certain speed to the boat ; we shall 
see that so long as this speed is appreciable^ the rudder 
acts efiSciently, and that the steersman has only to move 
it to the right or to the left at will to procure the evolution 
of the vessel. But let the rower rest on his oars, the 
boat, deprived of speed, will float " like a buoy," and it 
will be useless for the helmsman to work the rudder, as 
the latter will have no effect upon the boat, which will 
be the sport of the water on which it floats ; in order 
to steer it, we must propel it. 

In the same way we must " propel " an aerostat if we 
want to " steer " it. But to propel it we must have a 
motor, and every motor is necessarily heavy. Let us 
now inquire into the respective weights of the motors it 
would be possible to use. 

In the first place, there is the ^' human motor," that is 
to say, the muscular energy of the passengers in the car. 
It is hardly necessary to say that this was the first motor 
to be taken into account in the earliest days of aerosta- 
tion, for at that period it was the only one known. But 
though such a dream was possible then, it is so no longer, 
for the more precise data concerning mechanical experi- 
ments have established the weight-conditions of each 
category of motors. 

The practical unit of energy is steam horse-power, that 
is to say, a force capable of raising 75 kilogrammes one 
metre from the ground in one second. This power is 
very much greater than that of the animal horse. A 
man represents but a fraction of it. Now mechanicians 
have established by experiment, independently of all 
theory, that the weight of the steam horse-power 
translated into human muscular power, is about 1000 


kilogrammes ; in other words, it takes 1000 kilo- 
grammes of men to produce an effort equal to that of 
the steam horse ! It was therefore obviously futile to 
attempt to steer balloons by utilising the muscular power 
of the few aeronauts who controlled them. 

In the early days of steam power, motors were of con- 
siderable weight. The engine of the Sphinx^ the first 
steamship in the French Navy, weighed more than 1000 
kilogrammes per horse-power, and even thirty years ago 
steam motors weighed some 100 kilogrammes per horse- 
power. Hence the first steam engines were no more 
suitable for the propulsion of aerostats than human effort, 
to say nothing of the danger of installing a boiler heated 
by coal beneath an envelope inflated with hydrogen, an 
eminently inflammable gas. 

Nevertheless, steam was the power used in the first 
motor employed in a balloon. Its application was essayed 
in 1852 by the engineer, Henry Giffard. Instead of 
using the steam motors already in existence, he had 
one of 3 horse-power, expressly built for his experi- 
ment ; he succeeded in reducing the weight per horse- 
power to 53 kilogrammes; this was a remarkable 
achievement at the time and an enterprise of extra- 
or^nary audacity, taking its dangers into account. But 
the steam engine was very soon abandoned, owing to 
the risk of fire, and aeronauts adopted the electric motor, 
which, from 1880, was the recognised motor of the future. 
Colonel Benard succeeded in obtaining an electric motor 
of 8 horse-power, weighing only 40 kilogrammes per 
horse-power, and capable of prolonged action ; this made 
recU aerial navigation a possibility, and he had the glory 
of first accomplishing it in 1886. 


But about 1890 a new engine made its appearance; 
rude and clumsy at first, it was very soon improved and 
perfected ; thanks to this invention, a new industry was 
bom — ^the automobile — ^which has revolutionised all our 
habits. The engine was the ** explosion motor. ** 

The explosion motor is the lightest of any of equal 
power. To-day mechanicians have succeeded in reducing 
motors especially designed for aviation to the almost 
incredible weight of 2 kilogrammes per horse-power. 
Moreover, its action has been perfected ; it can start in 
an instant without any preparation. The volume has 
been reduced proportionately to the weight, so the engine 
10 not cumbersome. It is due to this invention that 
aeronautics have become what we see, and that aviation 
has been made possible in its turn. The explosion motor 
is the only one now used for aerial navigation. 


If we consider a machine able to give 100 horse-power 
for a weight of 1000 kilogrammes, we shall say that the 
** weight per horse-power "is 10 kilogrammes. But such 
data is insufficient for the aeronaut in working out his 
plans of construction. 

For we have not only to raise our machine, but to use 
it, to make it go, and for this we require a com- 
bustible, which in our particular case is petrol. Then 
we must have water to cool the motor, oil to grease 
its mechanism, and the accessories necessary for the 
working of the engine. In a word, if our 100 horse- 
power engine consumes 1 kilogramme of various materials 
per horse- power, it will use 100 kilogrammes of provisions 

]\ t- 




per hour. If we want to make it go for ten hours, it will 
require 1000 kilogrammes of provisions, the weight of 
which must be added to that of the machine itself. 

Thus, in the example we have taken, we shall have 
1000 kilogrammes, the net weight of the engine, and 
1000 kilogranmies of provisions, to enable it to run for 
ten hours, making a total of 2000 kilogrammea But for 
these 2000 kilogrammes we shall get 100 horse-power for 
ten hours — ^that is, 1000 horse-power hours. The weight 
per horse-power hour is, therefore, to be obtained by 
dividing 2000 by 1000; that is to say, it will be 2 

It is essential that we should not confound these two 
terms ; the weight per horse-power hour depends on a 
proper use of the combustible by the engine, whereas the 
weight per horse-power only depends solely on the con- 
struction of the engine. As Colonel Benard has already 
pointed out, it is possible to have the same number of kilo- 
grammes for the weight per horse-power hour with a light 
engine that consumes a great deal, as with a heavy engine 
that consumes very little ; but with too heavy an engine 
the balloon would not perhaps rise at all ; and the first 
duty of a balloon, even of a dirigible, is to rise into the air : 
ptimum vivere^ deinde phUosophcm^ said the philosophers. 

To conclude what we have been saying, we may lay 
down this principle : the motor should, above all things, 
be as light as possible; that is to say, the point of 
primary importance is to keep down the weight per horse- 
power. As to the diminution of the horse-power hour, 
this would merely enable us to prolong the duration of 
^e voyage, or, to use a phrase proper to naval warfare, 
to extend the '' radius of action " of the airship. 





The airship has often been compared to the steamship, 
the aerial ocean to the marine ocean ; is this a legitimate 
comparison ? We will briefly examine this question. 

We must first note the essential and absolute difference 
between an airship and a vessel. The latter floats 
upon an element of great density, the water, in which its 
propellers find an appreciable fulcrum, by virtue of its 
great resistance ; only a part of its hull is immersed, and 
it is upon this part only that the resistance which the 
surrounding liquid offers to the advance of the vessel is 
exercised. The balloon, on the other hand, is completely 
immersed in the liquid which sustains it by its vertical 
thrust, and this, due to the weight of a gas the thermal 
expansion of which is very great, varies every instant in 
accordance with the slightest vicissitudes of temperature 
or of barometric pressure, whereas the "hydrostatic 
pressure " which causes the ship to float upon the water 
does not vary appreciably when the temperature changes. 

But no floating vehicle, be it balloon or vessel, is ever 
required to float in a perfectly immobile element ; the sea 
is agitated by marine currents, such as the Gulf Stream, 
which circulates across the Atlantic, or the tidal currents 
at certain places on our coasts ; on the other hand, the 
atmosphere is in perpetual motion under the action of the 
" winds," which are aerial currents. There is, however, 
an essential difference between these two kinds of currents. 
Whereas the most rapid of the marine currents, such as 
the !^az de Sein and the Raz Blanchard do not exceed 


a speed of 9 knots (16*500 km. per hour), the aerial 
currents have often very considerable speeds. Directly 
the wind *' freshens," as sailors say, its speed is very soon 
increased from 10 to 15 metres a second, that is, from 36 
to 56 kilometres an hour. A ship, to which its engines 
give a speed which is very considerable in the most 
modem types (20, 25, and even 30 knots, or 37, 46, and 
55 kilometres an hour), will very soon overcome the ocean 
currents, the speed of which need only be deducted from 
that of the ship ; whereas the dirigible balloons are 
obliged to struggle against currents of air the violence of 
which condemn it to immobility-— or to retreat. 

In short, the ship and the dirigible balloon are not 
comparable. The only exact parallel of this kind which 
we could draw is that of the airship and the submarine, 
which is also completely immersed in the fluid which 
supports it. But the advantage is still on the side of the 
submarine, which never has to overcome the rapid currents 
with which its aerial counterpart has to contend. A 
juster comparison might be made between a dirigible 
balloon and a submarine which had to advance, not against 
a current, but against a torrent. 

We see how difficult a problem the propulsion and 
steering of aerostats is, and we can readily understand 
why it has taken a century to discover how to guide the 
machine which the brothers Montgolfier launched in the 
air for the first time in 1783. 



-nift ytiiiiigfHi <Hr mot ^Mmmsiiat:: T 


Wk m« ii&B«e^Hfoc« $<i^tt2|^ ttf» itdb^ tia aMOsta t» mud provide 
it Ytdli ;& «Ek><twr W^^n^ tit ;iai "^ taiiqp«nidMik qpeed ** which 
Yil^ iHttiiaiW itis p«v>|MdyMtt^)iaiil<iM^^ its directioiL 

Gttil vty«H^ wi^ ti&w^ pe^^pid Qwr jftnantrt^ it wiQ ex- 
pemoEii^f' m ntnttiteytM^ iEram i^ nrriNrndSng atmosphere 
lid ilb^ (K^rmo^l ttk^^wtt^^ mHMiS'vw we mttoB^ to dis- 
pibcie % Kvtr v^T^MJ^xrynil £dl ;ti ottiteraJ: ftni — fcr instance, 
ii wi^ ^rrt ^ m^^x^ % IS^uicvE w^iAdk w^ bdi ia our hand in 
tW >«rti^lMr — «^ )i^ ^ c>M«$Q;ttiiM ti^ ItW neyTHBait we are 
l»nH«^ |v^ f«v«i^NK '1^ o^^noiteiti^iiMi luA dqpeod upon 
kl^ >(v£wM vr 1^ lv^Qdt wks$^ ^^£ i{&a# Wdjr iftsplaced, for 
w^ ^Wit i^tr ^tl x^mtW ^NVi^iSuEi;^ 3ft t^;^ w&nHdbar we farj to 
t^vW tiW KwN^ ^JJ v*ir 9Kt^w W. Wd^ ^Jfe^ QK«e that the 
^rvw^^A!;^\V w^ je:t^«^5^^ iiC ^ ^/Qaj«^ sX^ood^QQiniii^ b«»ng equal, 
wv tint t^^ w.*x^ i;;i fl^w^^i^^. 

vHilS^. >»A^^ ;j^'4t^fw,y^x^,x 5v^ vWQ:^!h)i^ ^^d^ ■Wiwtj: vsf this ** air- 
^rwif^^nfc^K^ ' Vtii> ^x >rtCik^iH3t«w^ **i; t^:t^«tiit»»Lli. They 
i*A>n<^ *»:;:r;>twx 4i; '4*W i^.V^'jtr^^L sN"<nK)wtv«r^, W&K& is exact 
-.T ^i^ ^iJ^K,7> ^<5!i;^ tA^^> ;^^^.vw«ii5^ 'if wi^ demand 


precision : '* the resistance offered by the air to a surface 
element which is moving on a line perpendicular to its 
plane is proportional to the extent of this surface, to the 
square of the speed which animates it, and to a nimierical 
co-efficient, the mean value of which is 0125. The 
resistance is, thus, expressed in kilogrammes, if ihe 
surface of the moving element 
is measured in square metres, 
and if the speed is expressed 
in metres per second (Fig. 1)/ 
For instance, let us con- 
sider a panel, a board of 4 
square metres surface, moving 
normally to its plane at a 
speed of 10 metres per second; the resistance, in kilo- 
grammes, will be obtained by multiplying the surfitce, 
4, by the square of the speed, that is to say by 10 x 10, 
or 100, and by multiplying the sum by the co-efficient 

Fio. 1. BesiBtance of the air upon 
a normally moving surface 

Fio. 3. Influenoe of front shape 

0*125. It will therefore be the product of 4 x 100 x 
0*125, that is to say, 50 kilogrames. If the speed of 
movement be doubled, the resistance of the air will be 
quadrupled ; it would become nine times greater if the 
resistance were tripled — and so on. 

When the moving body is preceded by a " prow," that 

^ The reader who wishes to know the formula of the resistanoe 61 
the air, is referred to the Appendix at the end of the hook. 


is, a surface having tapering sides, which separate the 
molecules of air without striking them sharply as would 
a flat surface confronting them, the resistance is dimin- 
ished. Thus, if we take the panel of Fig. 1 , but cause it 
to be preceded by surfaces which will divide and thrust 
aside the molecules of air, as would be the case if we 
made use of the hemisphere or the cone (Fig. 2) with 
a base of the same superficies as the panel, the resistance 
of the air to the speed of 10 metres per second, which 
was 50 kilogrammes for the flat panel moving ortho- 
gonally, will be but 25 kilogrammes for the hemisphere, 
and only 9 kilogrammes for the acute-angled cone. 

Experience has shown that not only is the shape of 
the '' bow " of the moving body important, but also that 
of its " stern," that is to say of the " poop," for the 
profile of the latter may either permit an easy reunion of 
the molecules of air separated by the prow, and gliding 
along the sides to rejoin each other, or, on the other 
hand, its abrupt line may cause the molecules separated 
by the prow to re-unite tumultuously, clashing one with 
another and producing eddies behind the moving body. 


The points we have just considered must be taken into 
account in determining the shape of dirigible balloons. 

In the first place, there can be no question of attempt- 
ing to propel a spherical balloon ; the surface on which 
the resistance of the air iwould be exercised during the 
progress of the balloon would be enormous. With an equal 
volume of envelope, it is necessary to choose a shape that 
presents as small a surface as possible to the air as it 

be that of a mrmmisaxa^ tgnrift^, u. ri'nif ':ofj. uid. rf 
so, should k adracee -w^niL -dui acr^ :r I2« smfc'ier flsi 
foremost ? or KxsaJd h "ts » rrlniar ' 

Hie fins stc^iqxz. ^::ee teG^5fcri £z. :?5i, rf I>3j«m- 
de LAme in iS72. azri | 
of TiflBSodier in 1S^4. 
were made with ^fimr 
foiin"(s|HDdle-6haped I 
balloons; in other 
words, th«r shape, 
equally pointed at 
^ther end, was sym- 
metrical in relation 
to the central plan 

flmi ik«p« of tK^ra 

(¥ig. 3). Bat all this was chaoged when that man of 
genius appeared who was indisputably the real creator 
of aerial navigation. Colonel Charles Eenanl, whoiH* 
premature death in 1905 was an irreparable I088 to 
science and to France. 


Renard demonstrated by his calculations that the 
most advantageous shape is that of a dissymmetrical fisb 
(B), with the largest end at the front. So long ago as 
the beginning of the nineteenth century, Marey-Monge 
had presaged the necessity of adopting this form if an 
attempt should be made to propel aerostats : " They 
must have the head of a cod and the tail of a mackerel '' 
was his dictum. 

This, indeed, is the shape of all birds and of all swiftly 
moving fishes : whales, cachalots, and porpoises. At 
present all dirigible balloons which have proved really 
capable of progression are all constructed in the shape 
worked out by Renard. 

We must now point out that if the conditions of pn^res- 
sion and of the resistance of the air are to be normal, the 
balloon must preserve its shape during its course, either 
ascending or descending ; we sl^all see later how this 
condition is fulfilled by the " air ballonnet." 

As to the cylindrical form (C), adopted in Germany by 
Count Zeppelin, it seems less advantageous ; the mole- 
cules of air thrust apart by the point in front exercise an 
exaggerated friction on the sides before they re-unite, 
thus retarding the progress of the airship. The other 
•German aeronauts are therefore gradually returning to 
\the pisciform shape. 

In any case, the pointed end behind is indispensable, 
Tor without it there would be an eddy of the molecules 
of air, and consequently a partial vacuum which would 
cause antagonistic prow thrust ; this pressure, exercised 
against the forward movement, would retard the speed of 
the airship (Fig. 4) ; it is therefore necessary at all costs 
to avoid it by tapering the rear end of the balloon. 



The resistance of the air to the movement being pro- 
portionate to the square of the speed of the moving 
body, will lead us to a most important conclusion. It is, 
that balloons of large size have an advantage over those 
of smaller dimensions. Let me explain. 

To start with a clear idea, let us consider an airship in 
the shape of an oblong box with a square base, the latter 
being, for instance, 1 metre each side, by 5 metres long. 
Its volume will be 5 cubic metres, and its ascensional 
effort, taking this at 1 kUogramme per cubic metre, will 
be 5 kilogrammes. This balloon, if inflated with 
hydrogen, will, in round numbers, lift a motor the power 
of which will be limited by this weight of 5 kilogrammes ; 
and if we suppose that a motor weighing exactly 5 kilo- 
grammes per horse-power has been constructed, the 
motor this balloon can lift will be of one horse-power. 

Having demonstrated this, let us construct a second 
airship, exactly similar to the first, and also inflated 
with hydrogen, but with all the dimensions doubled; 
that is to say, having a squared base of 2 metres, by a 
length of 10 metres instead of 5. The volume of this 
balloon will not be double that of the first, it will be 
2 X 2 X 10, in other words 40 cubic metres ; that is, eight 
times larger, while its surface of resistance to progression 
will be that of its base, i.e., 4 square metres. 

Thus, as we have doubled all the dimensions, the 
resistance of the air will be four times greater, whereas 
the volume, that is to say the lifting power, will be txghX 


tixnea as much. Now, with a lifting power eight times 
greater, it will be possible to lift a motor eight times 
more powerful, and even mpre, for the weight per 
horse-power diminishes in proportion as the power of the 
motor increases. The balloon whose dimensions have 
been doubled will therefore have a motor of at least 
40 hors6-p6wer to meet a resistance of the air bearing 
upon four square metres, that is to say, 10 horse-power 
per one square metre of the transverse section, whereas 
the balloon of half this size will have only a 5 horse- 
power per one square metre of the section. The advan- 
tage is consequently all on the side of large balloons, and 
aeronauts who wish to undertake important journeys, 
and carry large stores of combustibles and numerous 
passengers, will find it profitable to construct dirigible 
balloons of large dimensions. The largest dirigible 
balloon yet constructed is the Zeppelin^ of 12,000 cubic 
metres, while the smallest is the Santos Dumont, No. 1, 
which gauged but 180 cubic metres; it is true that its 
only passenger, M. Santos Dumont, weighed only 52 
kilogrammes, and that the whole car weighed only 10 
kilogranmies ! 

To sum up, we may say that the volume, on which the 
power of the motor that can be carried depends, varies 
according to the cubic dimensions of the airship, whereas 
its surface, on which the resistance offered by the air to its 
progress depends, varies only according to the square. 

Finally, it is necessary to point out that the power 
necessary to communicate increasing speeds to the same 
airship increases proportionately to the cube of the speed. 
This law has been demonstrated by calculation and 
verified by experience. It is of vital importance, for it 


leads to various conclusions of the utmost moment. 
rhus, to double the speed of a dirigible balloon, we must 
^ve it a motor power not tvnce, but eight times greater 
(8 is the cube of 2 ; 8 » 2 x 2 x 2). We see therefore 
that great care is necessary in calculating the elements 
of a dirigible balloon, when it is destined to undertake 
journeys of any length. 


A dirigible balloon ought not, indeed, to be a mere 
object of scientific curiosity, or an instrument of sport ; it 
should have a useful application; it should be able to 
accomplish journeys. The longer these can be made to 
last, the greater will be the utility of the engine. 
Therefore it will be necessary, first and foremost, to 
ensure long-sustained flight in the ascents of this dirigible 

Here the question of speed plays a very important 
part, as does also that of the motor power it will be 
necessary to apply to the airship to give it the desired 
speed. This power, as we have just seen, is proportional 
to the cube of the speed. And this must be taken into 
account if travelling velocity is not the sole desideratum, 
and if the total distance the aerial vessel can travel is also 
an important factor. 

Let us consider a balloon of 3000 cubic metres, 
travelling at the rate of 60 kilometres an hour, with two 
engines of 60 horse-power each. These two engines 
would consume a total quantity of 60 kilogrammes of 
petrol an hour. The balloon, carrying six passengers, 
can take 600 kilogrammes of petrol, which will make it 
possible for it to travel for ten hours ; if we take into 


consideration that it has to retam to its mooring-ground, 
its pilot will have five hours of progress at his disposal, 
or, i*eckoning 60 kilometres to the hoar, 300 kilometres. 
We should say under these conditions that the radius of 
caelum of this diriffihle baUoan is 300 kUametres. 

Let us now suppose that only one of the motors is 
used ; the propelling power then will be only 60 horse- 
power ; the speed will be divided by the cubic root of 2, 
that is, in round numbers, 1*25 ; it will therefore be 
48 kilometres an hour. But the single motor will only 
consume 30 kilogrammes of petrol, and there are 600 on 
board ; the airship would therefore have twenty hours of 
trawl before it, instead of ten, that is, ten to go and ten 
to return ; it will therefore be able to travel 10 times 48 
kilometres, and still have the means of returning to its 
starting-point. We should therefore say that under 
these altered conditions^ the radius of action of the 
dirigible is 480 kilometres. 

Thus, by demanding a speed of 48 kilometres only per 
hour instead of 60, we extend the radius of action of the 
same dirigible from 300 to 480 kilometre& We have 
consequently increased it very considerably. 

This shows us how important this consideration of the 
radius of action is, especially in the application of aerial 
navigation to military or geographical matters. One 
thing should be clearly understood : speed is costly on an 
airship as on a transatlantic liner ; to double it, the 
motor power must be multiplied by 8 ; the balloon naust 
therefore carry eight times more fuel; whereas, by 
diminishing the motor-power by one-half, the speed is 
only reduced by one-fifth. When, therefore, airships 
attempt to perform long aerial voyages, the problem that 


confronts them will be, how to reconcile the minimum 
speed which will enable them to make way effectually 
against the prevailing winds, with a reduction of the 
motor power, which, by diminishing the amount of fuel 
consumed, will enable the store of petrol to hold out 
sufficiently to reach the most distant points! The 
wisest solution would obviously be to furnish the 
dirigible balloon with two independent motors ; when a 
** special effort " was required, the two engines could be 
used; but in favourable atmospheric conditions, the 
travellers would be content with the propulsion furnished 
by a single motor. Though the speed would be some- 
what diminished, it would be possible to travel a good 
deal farther. 

All we have just said of the " radius of action " of a 
dirigible applies of course to aeroplanes, for which this 
consideration is also of the greatest importance. 


The first condition to be fulfilled by our dirigible 
balloon, whether stationary or in motion, is that it 
should always be '' in equilibrium." 

When stationary, the airship should always maintain 
such a position that the geometrical axis of the solid 
body formed by its envelope is horizontal. Now when 
a dirigible balloon is suspended motionless in calm air, it 
is subjected to the action of two forces; one is its 
weighty P (Fig. 5), which is applied to the centre of 
gravity C of the system formed by the envelope and all 
it supports ; the other is the thrust of the air, applied to 
a point B called the centre of thrust. If the envelope 
contained only its inflating gas, and had neither car nor 


cargo to carry, and even if the weight of this envelope 
were negligible, the centre of thrust and the centre of 
gravity would coincide. But the addition of the weights 
that the envelope has to lift into the atmosphere causes 
this result : these two forces are not a continuation of 
one another. 

As they must necessarily be equal if the balloon 
neither ascends nor descends, it follows that they will 
make the balloon turn until they are a continuation 
of one another, and our airship will then take the 
position indicated by Fig. 5 (No. 2). 

To avoid this position, which would be incompatible 
with rapid propulsion, the weight must be properly 
distributed along the car fi*om M to N, in such a 
manner that, when the balloon is horizontal, the two 
forces, the pressure BQ and the weight CP, are upon 
the same vertical line. " Static equilibrium '* will then be 
ensured. We see therefore that the connections between 
the car and the envelope must never vary, though 
at the same time they must be allowed a certain flexi- 
bility, indispensable in aerial navigation. We shall return 
to this point when we deal with longitudinal stability. 

But this is not all ; the balloon, as it advances under 
the combined action of its motor, its rudder and the 
resistance of the air, must preserve a general stability ; 
it must remain perceptibly horizontal, and must not 
execute violent or extensive movements, either from fore 
to aft, or from right to left ; in other words, there must 
be neither ** pitching " nor " rolling." 

Every one knows what are the classic methods of 
aeronauts who go up in spherical non-dirigible balloons. 
To ascend, they diminish the total weight of their balloon 


by throwing out ballast, that is, part of a supplementary 
weight, composed of sandbags, which they take with 
them at starting. When, on the other hand, they want 
to descendf as they have no means of increasing their 
weight, they diminish the thrust of the air on the 

Fio. 6. Triangular connection suspension (indeformable) 

balloon by letting some of the light gas of the envelope 
(the specific lightness of which constitutes the lifting 
force of the balloon) escape from a valve. This ascen- 
sional efibrt diminishes in proportion to the amount of gas 
allowed to escape. The aeronaut is therefore able to ascend 
or descend at will by the dual means of ballast and valve. 
But this simple method cannot be applied to the 
conduct of a dirigible balloon. Dynamic equilibrium, 
that is to say the equilibrium of the airship in 
motion, must take into account not only its weight 
and the sustaining pressure of the air, but also 
the resistance of the air exercised upon its envelope, 
which resistance depends on ' the dimensions and the 
shape of that envelope ; in calculations, this shape is 
assumed to be invariable. Now what will happen if we 
allow a portion of the gas enclosed in the envelope to 


escape? When the balloon descends firom the atmo- 
spheric stratum from which the aeronaut wishes to 
approach the earth, it will find itself in masses of air, the 
pressure of which will increase as he comes nearer to the 
ground ; this will be easily understood, since theee 
lower strata bear the weight of the upper strata. The 
confined gas, now insufficient to fill the balloon, as a 
certain portion has been allowed to escape, will contract ; 
the balloon, no longer full, will become flaccid, and will 
not retain its original shape. The centre of resistance of 
the air will consequently have changed, as well as the 
centre of thrust, and the initial conditions will no longer 
be in force. As these conditions were used as the basis 
of calculations dealing with the equilibrium of the airship, 
that equilibrium can be no longer maintained. 


All these inconveniences are obviated by an ingenious 
contrivance, the idea of which originated with General 
Meusnier, who formulated it in 1784, only a year after 
the brilliant experiments of the Montgolfier brothers. 
Like all remarkable developments prematurely evolved, 
General Meusnier's idea was forgotten, and it was not 
until 1872 that the famous naval engineer, Dupuy de 
L6me, the inventor of the ironclad, resuscitated it in 
connection with his attempts to make balloons dirigible. 

We have seen above that it is absolutely essential to 
keep the balloon always perfectly inflated ; on the other 
hand, in order to descend, it is necessary to let out gas, 
which partially empties the envelope. To maintain the 
volume of this, it would therefore be necessary to take a 
stock of hydrogen to introduce into the envelope by 

Area of 


Air Pipe. 


means of a pump worked from the car. But when we 
consider that it would be necessary to carry this hydrogen 
compressed in very strong steel cylinders, we see, as a 
simple calculation will sufficiently prove, that the weight 
of the necessary number of cylinders would be prohibitive. 
Consequently, the 
aeronaut is obliged to 
reject this method, 
which is perfect from 
the theoretical point 
of view, but impracti- 
cable in fact. He will Fio. e. Air-Ballonnet 

rely, not upon a supplementary stock of hydrogen, but 
on air drawn from the ambient atmosphere, to restore 
the original volume, and he will replace the volume of 
hydrogen lost in the descent by an equal volume of air 
which he will introduce into the envelope by means of 
a pump. 

At the same time, the danger that would be incurred 
by sending this air directly into the envelope of the 
balloon must not be overlooked ; it would mingle with 
the remaining hydrogen, and we should thus have a gas 
not only as inflammable as hydrogen, but an explosive 
el^nent infinitely more dangerous. Here the ingenious 
artifice of the ballonnet comes into play. 

Instead of making the interior of the balloon a single 
capacity, constituting the whole interior, it is divided in 
two by a fribric partition liable to deformation (Fig. 6). 
This partition occupies the lower part of the balloon, and 
there forms a space called the air-haUonnet, terminating 
in a tube that descends into the car, whence a pump can 
charge air into it. 


When the balloon, at the beginning of its ascent, b 
completely inflated with hydrogen, this fisibric partition 
lies against the lower part of the envelope, exactly like a 
lining. If the balloon rises, the interior gas dilates, 
because the outer air becomes less dense, and a portion of 
this gas escapes through automatic valves ; the ballooii 
therefore remains fully inflated so long as it rises. If the 
descent begins, the gas, diminished by the quantity whidi 
has escaped during the ascent, no longer suffices to fill 
the envelope, which would then become flaccid, lose its 
original shape, and compromise the general equilibrimn. 

The ballonnet now comes into play ; by means of a 
pump installed in the car, the aeronauts force air into 
it, until the sum of the new volume it acquires and that 
of the remaining hydrogen gas, reconstitute the total 
original volume of the aerostat. In this way the mitial 
conditions of equilibrium are always maintained, in con- 
formity with the calculations of the constructors. 

There is obviously another way of ensuring this per- 
manence of form so necessary to the dirigible balloon ; 
it is to make the balloon rigid ; this last heroic solution 
has been adopted by Count Zeppelin for his gigantic 
balloon of 12,000 cubic metres, the Zeppdin. 

To ensure this invariability of form, the balloon is 
furnished with an absolutely rigid metallic skeleton, 
made of aluminium tubes. This framing is divided into 
several compartments, and a very strong yet light fisibric 
is stretched over the whole. This is the outer envelope, 
on which the resistance of the air is exercised during the 
progress of the balloon. In addition, there is, in the 
interior of each compartment, a balloon of air-tight 
rubber fabric, which is inflated with hydrogen. Thus 


the airship contains a certain number of balloons, the sum 
of whose lifting power constitutes the total ascensional 
effort. The external form is invariable, thanks to the 
material of the envelope and the framework on which it 
is BtretchecL 

We see at a glance, what colossal difficulties such an 
arrangement presents, the difficulty of constructing a 
trellised cylinder 120 metres long and 11 metres wide 
to say nothing of its expense ; the difficulty of fixing the 
external envelope, and finally, the complication of inflat- 
ing the elementary balloons contained in each of the 
compartments. Experience has shown the difficulty of 
managing such masses both at starting and landing : we 
shall return to this question later on. In any case it is 
difficult, and also very perilous, to give the body of an 
airship a rigid substructure. 


This question of stability is therefore of the utmost 
importance ; it is the basis of aerial navigation. 

Every one knows that the aerostat, whether dirigible 
or not, can rise or sink at will by the double action of 
the ballast and the escape- valve ; the skill of the aeronaut 
lies in economising the expenditure of these two essential 
elements ; the ballonnet, in these conditions, ensures the 
permanence of the exterior form. 

But this double action, expenditure of ballast and 
expenditure of gas, soon puts the aerostat hors de 
combat : it must therefore carefully preserve a sufficient 
stock of ballast to guard against the always possible 
dangers of a difficult or unexpected landing ; it must also 
preserve enough gas to be able at the last moment, to 


let out a portion of it and descend abruptly. Thus it 
has been found necessary to invent something else for 
dirigible aerostats destined to undertake long voyages, 
and this new appliance is the '' elevating rudder." 

A dirigible balloon, indeed, requires a motive power, 
which, through the intermediary of a propeller (generally 
a screw) communicates to it the independent speed 
without which it is impossible to steer it. But of this 
motive power, employed for horizontal propulsion, a small 
portion may be diverted which will serve for vertical 
propulsion ; that is to say, in the particular case we are 
considering, it will be used to make the aerostat rise or 
sink slightly, without any expenditure either of gas or 

The arrangement consists in providing the dirigible 
balloon with planes which can be inclined at will, known 
as "elevating rudders." These planes move about a 
horizontal axis, placed transversely to the axis of the 
balloon (Fig. 7), and may be placed in the middle, or 
fore or aft of the apparatus. In our figure, we have 
supposed that they are placed at the'back of the pisciform 
envelope ; a glance at these two figures will convince us 
of their controlling action; they raise or depress the 
** nose " of the balloon at will, just as the ordinary 
rudder turns it to the right or left. The same thing 
happens if they are placed in front. Generally speaking, 
it is difficult to fix them on the envelope itself, and they 
are placed on the car, as in the case of the ClSment- 
Bayard (Fig. 24), where we see this rudder, in the form 
of three parallel planes, fixed in front of the long car, 
immediately behind the screw propeller ; the apparatus 
is also called a " stabilisator." 


3Yating rudders may also be placed towards the 

le either of the envelope or of the car ; they then, 

rtue of the resistance they offer to the air, no longer 

to raise or depress the stern or the bow, that is to 

rection of Travel. 

ction of air resistance 
vpan the 

Elevating rudder 

ElevaiinjJ rudder 


Fio. 7. Action of the elevating rudder 

to incline the balloon, but to raise or depress the 
e body. 

has been proposed to get the same result by means 
rews with vertical axes, which would, of course, turn 
ontally ; their action, in this case, would have the 
J of raising or lowering the airship by exercising 
(ure on it either from above or below, according to 
direction in which they were worked. A more 
nal proposition is to joint the shaft of the screw, so 
it could be inclined either upwards or downwards, 
neither of these expedients is as simple or more 
cious than the elevating rudder, which is now in 
ral use. 


iloute Stability," or " Stability of Direction," consists 
16 following condition which the balloon ought to 


fulfil : its axis must always be at a tangent to the curve it 
describes if its course be curvilinear, and steered in 
accordance with the direction of this course itself if the 
latter be straight (Fig. 8). This stability is a quality 
which is exercised in the horizontal plane ; we must there- 
fore suppose that in Fig. 8 the dirigible balloon is seen 
from above and is travelling parallel with the ground. 

How is this stability to be ensured ? In the following 
manner : as soon as the balloon shows a disposition to 
diverge from the direction it ought to follow TT, a 
direction which is tangent to its trajectory, it must be 
brought back by the resistance of the air itself. For this 
purpose, constant use may be made of the " steering 
rudder," which, like the rudder of boats, serves to direct 
the airship from right to left. But this method would be 
fatiguing to the pilot, and not sufficiently efficacious to 
prevent unforeseen divergencies. Aeronauts, therefore, 
prefer to ensure stability of direction by the construction 
of the balloon itself, and this is the chief reason for con- 
structing our modern dirigible on the lines of the fish, 
with the larger end in front ; the centre of gravity of the 
balloon is thus brought to the front, and the "leverage'' 
of the stabilisating elements formed by the stern of the 
envelope is very efficaciously augmented. 

However, the envelope of the balloon itself would not 
suffice, so just astern of the latter *' stabilisating surfaces," 
have been disposed, formed of vertical planes fixed to the 
envelope, the sum of which form, as it were, the keel of 
th6 dirigible analogous to the keel of a ship. By this 
means, stability of direction is obtained naturally, without 
having recourse to the ordinary rudder, which is only 
used to obtain change of direction. 


We have still to consider "longitudinal stability." 
What is this third stability ? It is the property of 
remaining always 
horizontal or nearly 
80, which the balloon 
ought to retain, what- 
ever evolutions its 
pilot may cause it to 
make. In other 
words, it is the 
property of not 

" pitching. " J^io- 8- Rottte stability 

This longitudinal stability is much more important 
even than stability of direction. For should this latter 
be imperfect, the aeronaut corrects it readily by working 
his steering apparatus more frequently. But if longitu- 

ii Q tKrust 

P weigkt. 

The two forces 
BQ ct CP 
tending to 
of the balloon. 

Fio. 9. Longitudinal stability 

dinal stability is defective, the balloon may incline in a 
dangerous manner, and here the necessity of an unvary- 
ing connection between the car and the envelope appears 
more important than ever. 

If, in fact, the balloon and the car are united by un- 
yarying attachments, the suspension being triangular 


when in a state of equilibrium, the thrust and the weight 
are in the extension of one another ; if the balloon 
inclines, the car retaining its relative position, the weight 
is no longer in the prolongation of thrust ; but then the 
two forces tend to " trim " the airship. If, on the con- 
trary, the suspension is liable to displacement (Fig. 10), 
we see that if the dirigible inclin^ for some reason, its 
equilibrium would not be restored by the action of the 
weight of its car and cargo. 

The suspension must, therefore, be incapable of die* 
placement, and for this reason the idea of making the 
balloon rigid, and of uniting it to its car by rigid attach- 
ments has often presented itself {Zeppelin, Pax, for 
instance). But absolute rigidity involves terrible draw- 
backs ; all rigid balloons have hitherto ended by accidents. 
Aeronauts in general have decided in favour of triangular 
suspension (Fig. 9) ; these are sufficiently unvarying, as 
long experience has shown. 

One of the most serious causes of longitudinal instabi- 
lity lies in the gas which fills the balloon ; its tendency 
is to augment any inclination accidentally produced. 
This gas, by the very fact of its gaseous nature, is com- 
pressible, and on the other hand, the envelope of supple 
material, is essentially deformable. A transverse section 
of an inflated balloon would not therefore be a circle, but 
an ovoid figure (Fig. 11), the larger end of which would 
be uppermost. There are two causes for this : in the first 
place, the traction of the suspensory ropes of the car 
compresses the envelope laterally from A to B and from A' 
to B', making it almost flat ; in the second place, the 
interior gas, being lighter than air, tends to accumulate 
in the upper part, and this force obviously acts in the 


same manner as the preceding one, deforming the trans- 
verse section of the balloon. 

At a first glance, this deformation wotild not appear to 

/ ///////////////// 


Fio. 10. Instability prodaoed hy parallel conneotioni 

have any injurious influence on longitudinal stabiKty ; 
nevertheless, the last cause we have put forward may be 
adverse to this stability. 
Let OS suppose, for example, 
that the balloon is inclined, 
as in Fig. 12 ; the interior 
gas, which is lighter than 
air, will immediately rush 
to the upper part, leaving 
the lowered end. The latter 
will be insufficiently in- 
flated, whereas the former 
will be inflated to excess. 
The centre of thrust B 
will be displaced towards 
the right and as the two 
forces which would tend to restore the equilibrium of the 
balloon, BP and CP will be less and less distant one 
from another, this restoration will not take place. Such a 









\ *" 









upon form 


Fio. 11. Deformation of shape of 
transverse section 


contingency would be especially serious if the balloon were 
imperfectly inflated, for with a perfectly full balloon, this 
accident is less redoubtable. Thus the function of the 
ballonnet is doubly important, because it ensures per- 
manent inflation, and consequently persistent stability, 

. , .-.^. - ^^ - Destroy sc 

^ J^ //^ _\jzi longitudinal 

^,2 Division 4fi.. -■■^V'Oiil!^^**^'^'^ owin^ to 

t>l of ' ballonnet B >^ ^[n^^. displacement 

into 3 ballonnets ^w^l oF gas. 

bl b2 b3. 
bo prevent accumnlation 
oF air in B 

Fio. 13. Action of the ballonnet 

for the gas of the ballonnet, imprisoned in its special 
envelope, cannot accumulate in the lower part of the 
dirigible's envelope. Colonel Benard even di\'ided the 
ballonnet into several flexible compartments without 
any intercommunication in such a manner that the air 
contained in it could in no possible case accumulate 
by its own weight or inclination at either end of it 
(Fig. 12 B). 

Aeronauts have every reason to dread the inclination of 
airships, and to avoid them by every possible device. 
For the resistance of the material and of the suspension, 
&c., is calculated on the assumption that the airship will 
be horizontal, or very nearly so, in which case the strain is 
equally distributed throughout the suspension and on all 
the material. If, on the contrary, the airship should 
incline in an exaggerated and unforeseen fashion, there 
would be elements which take no strain at all, and others 

*>' ■ • ^- 

NrV.- V 



which would be loaded to excess ; grave accidents have 
resulted from such a cause. 

The operation of filling the ballonnet is consequently a 
most important mancBuvre in aeronautica Many con- 
structors now make it automatic : a pump is continually 
sending air into the ballonnet, and a valve in the latter 
opens as soon as the pressure of the air exceeds a given 
value ; the air it contains then escapes into the atmo- 
sphere, and the pressure resumes its normal value, ensuring 
the preservation of the form automatically. 

Axis of suspension. 


It was in 1904 that Colonel Charles Eenard first 
formulated the exact laws concerning the dynamic equi- 
librium of dirigible 
balloons, discovered 
the causes which ren- 
der this equilibrium 
precarious, and at the 
same time indicated 
be completely ob- 
Let us now 

Axis of suspension 

Fig. is. Imperfect equilibrium 

briefly summarise the results 
achieved by this distinguished officer. 

We will begin by noting that if we took a symmetrical 
fusiform balloon^ tapering equally at each end and sus- 
pended in a horizontal axis passing through its centre of 
gravity, this balloon would be in a state of ** indifferent " 
longitudinal equilibrium (Fig. 13). If the axis of the 
balloon is horizontal, and if a horizontal current of air 
bears upon it, the balloon will be in equilibrium, but an 


equilibriiun essentially *' unstable/' for calculation shows, 
and experience has proved, that so soon as the envelope 
thus suspended inclines ever so slightly, this inclination 
will increase until the axis of the balloon is perpendicular 
to the current of air ; in other words, till it assumes a 
vertical position ; this position is inadmissible, for it 
would amount in an airship to absolute instability. 

If, instead of a symmetrical fusiform balloon, we take a 
pisciform balloon, with the larger end in front, the insta- 
bility would still persist, though it would be considerably 
diminished, and here we are not in the domain of theory 
but of experience, for it was by dint of innumerable ex- 
periments, instituted with admirable method, that Colonel 
Benard obtained all the results we are now discussing. 
In the case of a pisciform balloon the disturbing effect is 
due, in unequal degrees, to the diameter of the balloon, its 
inclination and speed, whereas the stabilisating effect 
depends on the inclination and diameter of the balloon, 
but not upon the speed. The disturbing effect in the 
equilibrium therefore depends solely on the speed, atid 
augments very swiftly as the speed itself increases. 

It will, therefore, be easily understood that there is a 
certain speed for which the two effects are equal, and 
beyond which the disturbing effect, depending on speed 
will overpower the the stabilisating effect. To this speed 
Colonel Renard gave the name "critical speed" ; if this 
is exceeded, the equilibrium of the balloon becomes un- 
stable. The most remarkable feature of Colonel Renard's 
brilliant labours in this field is, that they are the expres- 
sion, no doubt, of learned calculations, but, above all, of 
experiments built up and conducted on a highly scientific 
method, experiments in which the gifted aeronaut sub- 


mitted keels of various shapes and dimensions to the action 
of a current of air which he could modify at will. 

We shall naturally ask if this ** critical speed " is very 
oonsiderable. We shall find that it is relatively slight, 
as the following numbers will show. Let us take, for 
instance, a dirigible pisciform balloon of the type La 
France ; its critical speed is 10 metres a second, or 36 
kilometres an hour, and a 24 hoi'se-power motor suffices to 
supply this speed. Now the lightness of contemporary 
motors is such, that a balloon of this type could easily 
lift a motor of from 80 to 100 horse-power. With this 
motor it might theoretically have a speed of 1 5 metres a 
second, or 55 kilometres per hour, but it could not 
accomplish this in practice ; for, its critical speed being 
36 kilometres, its equilibrium would become unstable if 
this were exceeded ; long before this speed was attained, 
in fact, the stability of an airship would become pre* 
carious and totally inadequate. 

It would therefore be useless to essay the lightening of 
the motor, that is to say the augmentation of the speed 
of balloons, unless we had a means of ensuring its 
stability, for, as Colonel Renard wittily observed in the 
case we have quoted : '^ If the balloon were provided with 
a motor of 100 horse-power, the first 24 would make it 
go, and the other 76 break our necks." 

This means of stabilisating is the '' empennage," that 
is to say, the systematic use of rigid planes, both 
vertical and horizontal, passing through the axis of the 
balloon, and placed very much behind the centre of 
gravity ; the resemblance of a balloon thus armed to a 
leathered arrow is obvious, hence the name of the 


With a balloon of the size of La France (60 metres 
long and 10 metres in diameter), the surface necessary 
to achieve strict emp^nation^ i.e., to annul the disturb- 
ing effect, is 40 square 
metres, lying 25 metres 
behind the centre of 
gravity. By slightly 
augmenting the surface 
and the distance, a degree 
of security higher still is 

But how is this " em- 

Fio. 14. Crucifonn ^empennage of the 
Patrie and lUpuhliqut 

pennation " to be carried out ? In the Lehaudy balloon 
it was fulfilled by means of surfaces afiixed to the 
framework between the balloon and the car; in La 

Vaie de Paris 


Fia. 15. Pneumatic empennages 

Patrie^ a still better plan was adopted; the feathered 
arrow has been literally realised by fitting four sur- 
faces in the form of a cross to the stern of the 
envelope, as shown in Fig. 14. Colonel Renard pointed 
out another method of obtaining the effect of the em- 
pennage without the use of rigid planes, difficult to fix 
to the envelope of the airship and tending to overload 

V - r 



the prow ; this was to affix to the extremity of the enve- 
lope elongated ballonnets projecting from the body of the 
balloon. This miethod was adopted by M. Surcouf in two 
different forms : cylindrical ballonnets for M. Deutsch's 
Ville de Paris (Fig. 15), and conical ballonnets for M. 
Clement's Bayard. Inflated with hydrogen, these bal- 
lonnets exercise a pressure which compensates for their 
weight, and they no longer constitute a useless and 
unsymmetrical supplementary load to the airship. 

There are obviously other means by which instability 
in motion may be counteracted ; the use, for instance, of 
a very elongated car, which allows a considerable weight 
to be displaced from stem to stem; this method was 
EMlopted in the Zeppelin ; but such an arrangement is 
difficult to work, and the '' empennage " is at once simpler 
and very much safer. 


Where should the motive power which is to propel the 
dirigible balloon be applied ? At what point of the com- 
plex system formed by the envelope and its accessories 
should the propulsive force act? We have still to 
examine this question. 

As the essential sustaining part of the airship is the 
envelope, it is this which offers the maximum resistance to 
the air. Theoretically, therefore, the propulsive effort 
should be applied to the axis of the balloon itself, and so 
Qoany inventors have thought ; several have attempted to 
(naterialise this theory, notably the unfortunate Brazilian 
Severe d' Albuquerque in his balloon Paa^^ which ended in 
\ catastrophe, and the constructor Rose, who produced a 


twin airship, the axis of the screw being between the two 
balloons which constituted his system. 

This conception would be a perfectly just one if the car 
and the rigging offered no resistance to the air ; but their 
resistance is far from negligible. The car has a transverse 
section of several square metres, and the sum of the sur- 
faces presented by the suspensory ropes is enormous. To 
give an idea of this, let us take these to be steel cords of 
three strands, each of three threads, that is, nine threads 
to the cord ; their diameter is about three millimetres, 
their length between the car and the balloon about ten 
metres. One of these ropes would therefore offer a 
resisting surface of about 300 square centimetres or three 
square decimetres ; ten of these cords would thus represent 
a surface resistance of about one-third of a square metre, 
and sixty cords would equal two square metres. Add to 
this the sum of the sections of the knots, splices, pulleys, 
ropes used in the working of the vessel, transverse membei'S 
which serve to send compressed air into the ballonnet by 
the special pump, the surfaces of the rigging, guide-ropes, 
&c., and finally, the surfaces of the passengers, and you 
will soon arrive at a sum of resisting surfaces, exterior to 
the sustaining envelope, and equal to a quarter, a third, 
and even more of a transverse section thereof. K, there- 
fore, we represent the resistance offered by the envelope as 
BR (Fig* 16), and that offered by the car and its acces- 
sories as CR', the motor-power AF must be applied at 
the point A, between B and C, and nearer to B than to C, 
to ensure the permanently horizontal position of the system 
under the combined action of motor and resisting effort. 
But, on the other hand, it is difficult, at least in the present 
state of aeronautic construction, to fix the shaft of the 

Fio. 16. Application point of tho 
propelling force 


¥ to the envelope itself, without using rigid envelopes 
those of the Zeppelin or the Pax. Perforce, therefore, 
leronaut has to be content with an application of the 
>r power to the car itself. Hence a tendency in the 
;ible balloon to tip up at the nose, because the force 
lot exercised directly 
he point of applica- 
A, the resultant of 
^wo forces R and R^ 
constant use of the 
iting rudder becomes 
3sary, and we find 
thistiltingisthe more 
ounced the farther 
»r is from the envelope. The term " deviation " is 
to describe this tilting effect produced by the action 
le propeller. 

will be readily understood that this " deviation " will 
lodified in proportion as the car is brought closer to 
balloon ; but this approximation is limited by the 
:er of installing a combustion engine too close to an 
lope containing an inflammable gas. The golden 
1 must therefore be observed. If the car were too far 
the balloon, the tilting effect would be very great, 
the balloon would incline without advancing, 
le Comte de la Yaulx has found a very ingenious solu- 
of this difBculty. It consists in fixing the screw H 
17) to a shaft HK placed at a height between the 
lope and the car. The latter contains the motor 
h works the shaft HK through a transmission system. 
is a very rational solution, and it is probable that it 
be widely followed in airship construction. 


As to the position of the screw, this may vary consider- 
ably : Colonel Benard and M. Surcouf, the constructor of 
the balloons Bayard-ClSment and Ville de Paris, place 

it at the prow of the car ; 
under these conditions it 
draws the balloon. Other 
constructors place it at 
the stern ; this was the 
plan adopted by Gifl&rd, 
Dupuy de L6me, and the 
brothers Tissandier. M. 
Julliot, the engineer, to whom we owe the Lebaudy 
and the Patrie, introduced two screws, which he fixed 
outside the car, on either side and almost at its 
centre. We see then that various arrangements are 
in use. But on the whole there seems to be a preference 
for the screw at the prow of the car. 

Fio. 17. Rational arrangement of 
the screw 



The chief enemy of the aeronaut : How the wind inter- 



Thb wind is easy to define : it is the movement of 
atmospheric masses in a* horizontal direction, the dis- 
placement of air parallel to the surface of the earth. The 
study of the winds is one of the principal objects of that 
branch of physics called meteorology. 

Meteorology, or at least the study of atmospheric 
phenomena over continents, otherwise called *' Con- 
tinental meteorology," is relatively backward, com- 
pared with nautical meteorology. The reason is that 
above oceans the immense and uniform surface of 
the waters allows molecules of air to obey the laws ot 
equilibrium and the movement of fluids freely, whereas 
the surface of the land, bristling with an infinite variety 
of obstacles, ofiers much greater di£Bculty to the estab- 
lishment of clearly defined rules. Moreover, the waters 
of the sea cover nearly three-quarters of the surface of 
the terrestrial globe ; it is above them, therefore, that 
the great laws of the movements of the atmosphere are 
demonstrated ; finally, all sailors are meteorologists, 
whereas keen observers are rare on land ; this fact has 



given rise to the sarcastic definition of meteorology as a 
science which consists in knowing what kind of weather 
it was yesterday. 

Yet it is with the winds that blow over continents 
that aeronauts will have to reckon, at least, in their early 
days, for the moment has not yet come (though, indeed, 
it may not be far distant) when, launching themselves 
audaciously over the waters, they will have to struggle 
with oceanic winds, and consequently to experience 
personally the laws of nautical meteorology. 

The wind is differentiated by its direction and its 
velocity, or its force. Its direction is indicated by naming 
the point of the horizon whence it blows : a north-east 
wind is a wind which blows from the point of the horizon 
situated in the north-east, &c. ; the so-called ^* compass- 
card " of the mariner gives all directions of wind by their 
initials (Fig. 18). 

The velocity of the wind is reckoned by metres per 
second. We should say, for instance, a wind of 7*50 m. 
per second. By multiplying the speed in metres per 
second by the factor 3600, the number of seconds in an* 
hour, we get the speed of the wind in kilometres pof 
hour. A wind of 10 metres a second is, therefore, 86 
kilometres an hour ; the wind of 7*50 m. corresponds tD 
26 kilometres an hour. 

The force of the wind may be measured by the pressme 
it exercises upon a motionless obstacle normally opposed: 
to it. Sailors have deduced from centuries of navigatum. 
in sailing-vessels that the pressure of a wind making a 
metre per second upon a surface of one square metre 
perpendicular to its direction is 0*125 m., or, in correct 
language, 125 grammes to the square metre. This pressure 



ITHF ^ ■ 


. r 

won Llhi** ' 


increases in proportion to the surface of resistance, and in 
proportion to the square of the wind's speed. For a wind 
of 2 metres per second, it vould therefore amount to 
4 X 0*125 kg., or 500 grunmes per square metre ; for 
a wind traveUing at a speed of 4 metres, it would be 
16 X 0-125, or 2 kilo- 
grammes per square 
metre, and so on. 

When the speed of 
the wind becomes 
considerable, the pres- 
sure it exercises upon 
fixed obstacles be- 
comes in its turn 
enormous ; a wind of 
25 metres per second, 
or 90 kilometres an 

hour, would esercise FI°- IS- Compasx-card 

a pressure of 25 x 25 x 0-125, or nearly 80 kilogrammes 
per square metre. The accident which resulted in the 
loss of the dirigible balloon La Pafrie was due to this 
formidable pressure. 

I i 




Let UB now deBue this idea of the wind rather more 
pTecieely, for, in the special case we are studying, an 
uiaccurate idea of it is often formed, and it must not be 
iwgotten that it is in the very bosom of the atmosphere 
th&t we encounter it with our dirigible balloons. * Let us 
fterefore study the wind, not in its relation to the ground, 
^t in its relation to the airship. 

If we were in a spherical balloon, it would be bus* 


ceptiUe to iins pr eaB ure ao long as, mpnx»8B of inflation, 
it were held to the grooiid by mooriiig ropea; this 
" force of the wind " would tend to beat it down upon 
the groond or to tear it firom the hands of those who 
were holding and keeping it stationary. Bat so soon as 
its moorings are cast off, so soon as the balloon rises into 
the air without any propelling mechanism, the aeronaut 
is conscious of afasolate calm: the wind, in &ct, is 
imperceptible to him, because the wind is a relcUive 
movement of the molecules of air in respect of an 
observer stationed upon the ground. Once in the air, a 
spherical balloon forms part of the atmosphere. It is 
carried along by the wind itself, and moves with it; ib 
not displaced in relcUian to it. So long as the ballocm 
neither rises nor sinks, a little banderole £BU»tened to the 
rigging hangs vertically, without fluttering as it would do 
under the action of the wind if it were fixed to the ground. 
Thus, for the (Aeronaut who belongs^ not to the earthy 
hut to the atmosphere^ ivind does not exist ; these are the 
very words used by Colonel Renard the first time he 
described in public his definitive experiments upon the 
steering of balloons. If then we were to take an airship, 
dirigible or otherwise, everything in connection with it 
would happen as if the air were motionless. If the 
balloon is dirigible, that is to say, if it is furnished with 
a motor and a propeller, and if these forms have been 
duly studied, the aeronaut could move in this atmosphere 
in every direction, as if the wind did not exist ; as his 
balloon* advanced, he would have the same sensations as 
if he were passing through an absolutely calm atmo- 
sphere. He would have an impression of wind, but this 
wind would have no relation to that which blows over the 


surface of the earth ; it would be a current of air from 
the stem to the stem of the balloon, and this wind would 
he created by the aeronaut himself in his progress ; it 
would be the result of the displacement of the balloon 
under the action of its screw. Should he stop this, calm 
would be at once established, and the aerial navigator 
would no longer feel the slightest current of air. 

To sum up, then, we may say with Colonel Renard that 
<< the balloon belongs to the air and has nothing to fear 
firom it If it is furnished with a propeller and a motor, 
in a word, if it is dirigible, the wind changes nothing, 
either in the nature of the efforts it has to undergo 
during the voyage or in the speed of its displacement in 
relation to the aerial ocean in which it floats : and every- 
thing goes on as if, the air being perfectly motionless, 
the earth were flying beneath it with a speed equal and 
contrary to that of the wind." * 

In the case of the aerostat, as of the airship, the wind 
therefore means, from the point of view of a final result, 
a relative displacement of the ground, exactly as if the 
aerial swimmer being motionless, the earth were carried 
along by the current of air. From this we shall note 
interesting results, which will show us the limitations 
of the efficacious action of dirigible balloons. 


Let us imagine an "aerial fleet"" (Fig. 19) hovering 
over Paris, composed of a central balloon, playing the 

^ GoIoDel Oh. Benard : La Nfmgaium ahiennef a lecture delivered 
•ft a meeiiiig of the Sooi6t^ dee Amis de la Science^ April 8, 1886. 
s IKd. 


part of flagship, and six " aerial cruisers " ; the admiral's 
baUoon occupies the centre of the circle formed by the 
Btx cruisers ; all the engines have stopped, and the flottlk 
is for the moment motionless in relation to the air. The 
wind is west, blowing at a speed of 8 metres per second, 
that is to say, 29 kilometres an hour. 

FiQ. IS. Biainple of nlatlvs wiod 

At this moment the admiral's balloon issues an order : 
the six cruisers are to effect a reconnaissance, each going 
off in a different direction, while the balloon in command 
will remain motionless to await their return. Let qb 
imagine all these cruisers travelling at the same speed 
of 6*50 metres a second, for instance, or 22 kilometres an 
hour : this is the independent speed of each in calm air. 
At the end of an hour they would all be 22 kilometres 
from the admiral's balloon ; in other words, they would 
be distributed on the circumference of a circle with a 
radius of 22 kilometres, the geometrical centre of which 
would be occupied by the balloon in command. This is 
what would be happening tn the air. Now let us see 


how our seven balloons have been disposed above the 
ground^ taking into account the wind, which is blowing 
at the rate of 7 metres a second, or 29 kilometres an 

The earth will appear to have fled towards the west 
precisely at the speed of the wind, that is, 29 kilometres 
an hour. Thus Paris, which was just now immediately 
under the admiral's balloon, will be removed 29 kilometres 
west of the airship, which, having stopped its engine, 
has remained motionless in the air. Below this balloon 
will stretch a new region, that of the Marne, and Lagny 
is now the centre of the circle with a radius of 22 kilo- 
metres, on the circumference of which the six aerial 
cruisers are symmetrically distributed. Consequently 
the west wind has really had no effect but that of dis- 
placing the whole aerial fleet en bloc towards the west 
by a distance of 29 kilometres under the wind. It has 
therefore made no change in the relative positions of the 

Armed with this result, we may now determine the 
points which the dirigible balloon could attempt to reach, 
taking into account its independent speed and the 
velocity of the wind. 

Let us imagine our balloon furnished, by means of its 
motor and its screw, with an independent speed of 
6*50 metres per second; this, as we have already 
explained, amounts to saying that in absolutely calm air 
this balloon would travel 22 kilometres to the hour. 
Let us suppose that this independent speed differs from 
that of the wind, which we will take to be 8 metres a 
second (29 kilometres an hour). The balloon starts from 
the point P (Fig. 20), in the direction PA, at an inde- 


pendent speed represented by the length, PB : this 
would mean that, if there were no wind, at the end of 
an hour it would have arrived at B. But the wind is 
blowing in the direction PS at a speed represented by 
PV : the balloon will therefore travel along the route 
indicated in length and in direction by the diagonal PR 
of the parallelogram BPVR, and at the end of an hour, 
under the combined action of its own speed BP and that 
of the wind, PV, it will have arrived at the point R, 
having throughout preserved the direction represented 
by the silhouettes (1) and (2). Consequently, should 
the speed of the wind be greater than its own, and 
should it be directly opposed to this, there would 
be regions in the atmosphere access to which would 
be impossible to the balloon, which could only by 
using its motor deviate from the direction of the wind, 
as is shown in Fig. 20. We will now inquire more 
closely into this question. Three cases might present 
themselves : 

1. The independent speed of the balloon is less than 
that of the vnnd. (Fig. 21.) Let P be the starting-point 
of the balloon, and let us take the line PA to represent 
its actual speed. This means that if the air were calm, 
at the end of an hour it would find itself somewhere on 
the circumference of the circle C, the centre of which is P, 
and the radius of which corresponds to this speed PA. 
But the wind is blowing with a speed V, greater than v : 
accordingly, all the circle, C, finds itself at the end of an 
hour transported to C, and the balloon will find itself 
somewhere on this new circle C, which is, from this very 
fact, the circle of points approachable in the space of an 
hour, the distance, PP', being equal to the speed of the 





V s 

Fifl. 3Q. Combined effaoU o( wind and 
Independent ipaed 


wind. The otUy points of the ^xtce which the balloon could 
reach would therefore he those which woiUd be comprised 
within the angle 
formed by the tan- 
gents leading from 
the point V to the 
circle C, that is to 
say, comprised in 
the r^on which is 
iAiaded in the figure. 
All the rest would be space iaaccessible to the balloon. 
The accessible angle will consequently be greater, the less 
difference there is between the speed of the wind and that 
of the balloon. This space would be nil if the speed of the 
balloon were itself 
nU; this is the case 
with free balloons, 
which can only 
move along the 
line PF. 

2. The indepen- 
dent speed of the 
balloon is equal to 
that of the wind 
(fig. 22). — The balloon is at the point p, its actual 
speed is PA, equal to the speed of the wind ; if the 
wind were not blowing, at the end of an hour the 
balloon would be somewhere on the circumference of the 
drcle ', but the wind is blowing with the speed PP', 
exactly equal to that of the airship itself; the circle is 
therefore transported to C, and it is on the circumference 
of C that the balloon finds itself at the end of an hour. 



' I" 






Fio. U Ou« whan tho indapNideiit ipaed 
equkli tha wind 


The shaded angle of the former example, which has 
become more and more obtuse as the values of the 
two speeds approxi- 
mated, becomes equal 
to two right angles, 
and tba aooessible 
r^on oom[uisee tiie 
entire half of the 
space, thatwhiob is to 
the right of the tan- 
gent leads from the 
point Pto theoiroIeC. 
S. Themd^iendent 
speed of the baUom 
is greater than that of the wind (Fig. 23). — In this ease 
there is oo special anglewhich limits the acoeasible runona; 
the whole apace is acces- 
sible to the airship, even 
in the direction contrary 
to that of the wind, and 
if the balloon goes 
straight against the 
current of air, it will 
advance in respect to 
the ground with a Bpeed 
equal to the difference 
between its own apeed 
and that of the wind : 
all space is there/ore accessible to a dirigible balloon 
whose indepejvient speed is greater than that of the wind. 
This last condition is the essential and sufficient condi- 
tion of perfect dirigibility. 

Fia. 2). The balloon ipeed !■ gntiM Uiu 
the wind, ao it can go anrwhera 

PUBLK" ll-%,A. . 




We know now under what conditions an aeronaut 
ould hope to reach any given point. Are these con- 
itions compatible with the average state of the atmo- 
phere, in other words, with the average speed of the 
rinds that prevail in our regions ? Here we must rely 
n observation alone for a satisfactory answer. 

Our official meteorologists are silent on this point in 
beir treatises, as on many others ; so it has been requisite 
)r our aeronauts to make the experiments necessary to 
btain the results indispensable to them. Such experi- 
lents have been carried out for many years at the 
iilitary establishment of Chalais-Meudon. The very 
iteresting results are summarised in the following Table. 
a this Table, the first column gives the speed of the 
'ind in metres per second ; the second, the correspond- 
ig speed in kilometres per hour ; the third, in fractions 
P a thousand, the possibilities of encountering a wind of 
le velocity denoted. Thus, for instance, if we take a 
ind of 5 metres a second, or 18 kilometres an hour, 
le possibility of having a lighter wind will be 323 
lousandths, in other words, there will be 323 chances 
> 1000 that the wind will be blowing at a rate of less 
lan 18 kilometres an hour. The fourth column indi- 
itee the number of days in the year when, on an 
i^erage, a wind of less velocity than those indicated in 
le first two columns will be prevailing. These final 
gures are therefore those which will throw most light on 
le present conditions of dirigibility for the aeronaut. 

We must remember that these figures apply to the 


vicinity of Paris, where the obserratioos on which Uiej 
are based were carried out. 

Speed of the wind 

fi|*ed of th< wind 

FoMibiUtiM (in 
pKrU of a UiouuDd) 

Uist the wind 

relocitj will ba loa 

than tbat of the 

first two ooluaiu. 

Id the jew what 
there would Ua 


in kilometre* 
PM bour. 

relocitj Sebg Urn 
than tbat of tbt 
fint two oolonna. 












7- BO 




























25 00 




27 50 
































The importaDce of these results is at once apparent, 
especially if we translate the average chances of the 
wind into " numbers of days per year," as I have done 

Thus, let us take the speed of 10 metres a second, or 
36 kilometres an hour ; accordiog to the probabilitiee 
arrived at by these long series of observations, there are 
258 days In the year when the speed of the wind in the 
neighbourhood of Paris is, generally speaking, less than 
36 kilometres an hour. Therefore a dirigible ballooD 


with a speed of 10 metres a second could make way 
against the wind, on an average, 258 days out of 365 ; 
if the balloon has a speed of 12*50 per second at least, 
that is to say 45 kilometres an hour (which is the speed 
of the Bayanrd-CUment^ the Repuhligue and the Vxlle de 
Paris), we see that it would be dirigible on an average 
297 days out of 365, that is to say, about ten months 
out of the twelve. Now, as I have already stated, this 
is the speed actually maintained by all modern airships. 

We may therefore affirm, figures in hand, that the 
problem of aerial navigation hy dirigible balloons is 
completely solved. 

Of course there are exceptional cases: thus, the 
average probability of winds travelling faster than 
35 metres a second, that is to say, hurricanes blowing at 
a rate of 125 kilometres an hour and even more, is nil^ 
or almost nil; in other words, 999 times out of a 
thousand the chances would be in favour of a less violent 
wind. Such winds, however, do occur occasionally, but 
they are accidents ; they devastate gardens, and damage 
buildings, and are, I repeat, exceptional eventualities. 

There is, nevertheless, one important remark still to 
make on the velocity of the wind ; this is that the speed 
of atmospheric currents augments very rapidly as we 
rise in the air. In Paris, for instance, owing to the 
Eiffel Tower making it possible to observe these effects, 
whereas the average speed of the wind in the course of 
the year is about 2 metres per second on the level of 
the houses (7*200 km. per hour), it is over 8 metres at 
the top of the tower (about 29 kilometres an hour). 
Aeronauts must therefore take this circumstance very 
carefully into account, if they wish to form an accurate 


idea of the power of the wind against which their 
balloons will have to struggle when the voyage is to 
take place, not just above the earth, but at a certain 
height in the atmosphera 

We see, too, that if constructors accomplish the short 
stage connoted by the next advance in aeronautics, that 
is to say, if they achieve a speed of 20 metres per second 
or 72 kilometres an hour for the '* independent " speed 
of airships, these will be able in our regions to travel 
350 days a year; this would be absolute solution, for 
the days when the speed of the wind is higher than 
20 metres a second are days of clearly defined bad 
weather, and are fortunately not very frequent. 

Progress will therefore consist in augmenting the 
power and the output of the motor and in improving the 
quality of envelopes, which must be made capable of 
resisting the increased pressures of the air caused by the 
greater speed of flight in the future. 




Appucation of the prxccdino principles : How to construct 
an airship : how to arrange the motor and propeller : 
The two rudders : What are the travelung sensations in 

A dirigible ? 


Ws have just shown what are the fundamental prin- 
ciples of aerial navigation by dirigible balloons. We 
must now see how these principles are applied in the 
construction of those airships from which practical results 
may be expected. 

The construction of the envelope is the first thing to 

be done. We have already said that it must be light, 

strong, and impervious to hydrogen. All, or practically 

all, modem dirigible balloons have envelopes of rubbered 

material, consisting of two layers of fabric with a layer of 

robber between them. This material weighs 300 grammes 

per square metre, and will bear a strain of 1800 grammes 

per metre. Very often, after the envelope is constructed, 

it Is coated with a layer of chromate of lead, to arrest those 

Bolar rays which, by their actinic action, might affect 

the rubber ; it was this colouring matter which gave 

M. Lebaudy's balloon the ^^ yellow " tint, and suggested 

Its popular nickname. 



The outline of the envelope is important, for the 
exterior form of the airship ought to correspond to the 
minimum of effort required for propulsion in the air, 
while ensuring longitudinal stability. Thus the curved 
outlines of modern airships have been studied ¥rith the 
utmost mathematical precision. 

The modem balloon should, following the indications 
given by Renard, be pisciform, with the larger end 
forward, after the manner of fishes and birds, otherwise 
there will be a risk of low efficiency (examples of which 
will be given in the following chapter). But the profile 
and the elongation have still to be considered. 

The envelopes constitute what is known in geometry 
as '' surfaces of revolution," in the sense that they may 
be considered as engendered by the rotation round thttr 
longitudinal axes, of the curve which defines their profila 
The constructor begins by fixing the length of the 
balloon, its maximum diameter, and the position of the 
latter in the length of the envelope ; after this he calcu- 
lates the profile, generally formed since Renard's time, of 
two parabolas united ; these parabolas are either simple 
or of the superior degree ; but these are mathematical 
details which I need only indicate. WKen the envelope 
is calculated, it is drawn, and the diagrams necessary for 
cutting out the pieces of material are made ; these 
pieces, sewn together, constitute the body of the 

We will take as our type of a dirigible balloon the 
Clement-Bayard^ which Parisians have so often seen 
floating above their city, and which is familiar to me firom 
the fact that I have made various ascents and voyages 
therein ; the perfection of its construction and the 


accuracy of its evolutions give it a right to be cited as a 
sample of French aeronautics. 


The silhouette of the envelope (Fig. 24) is formed by 
two parabolas of the third degree. The envelope is 
made of panels sewn together ; its total volume is 3500 
cubic metres. 

Its surface is 2250 square metres. It is 56*25 metres 
in length and the maximum diameter at its largest 
section is 10*58 metres. This envelope is inflated with 
pure hydrogen gas ; in spite of the high price of this gas, 
which costs 1 franc and sometimes more per cubic metre, 
it is preferred to illuminating gas, no matter how cheap 
this may be, on account of its great lifting power ; and 
balloon-material has become so perfect that it reduces 
the loss of gas by exudation through the rubbered fabric 
to an insignificant percentage. 

In the middle of the envelope there is a ripping valve, 
this is an aperture in the upper part of the envelope 
covered by a band of fabric which can be torn ofl* in an 
instant by pulling a cord, should a rapid descent become 
necessary ; this manoeuvre can be carried out from the 
ear. At the end is the pneumatic empenruigef consisting 
of four spherico-conical ballonnets, tangent to the back 
part of the envelope and communicating therewith 
through holes. The air-ballonnet proper is divided into 
two parts ; it is 23 metres long, and has a volume o^ 
1100 cubic metres. 

The balloon is furnished with four automatic valves ; 
two for the hydrogen gas, which automatically open as soon 


as the preesure equals 40 millimetres of water, and two 
for the air, opening when the pressure equals 30 milU- 
metres. These two pressures are indicated by two 
manometers fixed under the eyes of the pilot, on the 
firont of the bridge. If a valve were not working 
automatically, he would therefore be warned, and could 
work it himself by pulling a cord. The air is continually 
pumped into the ballonnet by a fan which can pump 1800 
litres per minute, and this is actuated through trans- 
mission from the motor. When this stops, the &n can be 
worked by hand. 

The suspensions are thin steel cables of three strands, 
each of three threads. Some of them are 3, others 
4 millimetres in diameter, and they can bear respectively 
a strain of 400 and 600 kilogrammes. They terminate 
in " goose's-feet " of hemp fastened to boxwood 
stakes, and the latter are encased in a "girth'' sewn 
into the fabric, which forms the envelope of the balloon ; 
the net is thus rendered unnecessary, and this facilitates 
the passage of the molecules of air along the envelope, by 
dispensing with the resistance offered by the asperities of 
loops and knots. 

Beneath the " suspension girth " is placed the liftbg 
girth, also sewn to the fabric. The "lifts" are steel 
ropes, which are oblique in relation to the length of the 
balloon, and ensure the indispensable triangular suspen- 
sion that secures the solidity of the car and the envelope, 
both in longitudinal and lateral directions. These lifts 
connect together by four " knots," which also constitute 
the fixed points of the suspension. These knots may be 
distinctly seen in the diagram. 




The car is built up of a series of cubes of steel tubes of 
30 and 40 millimetres diameter. The sides of the cubes 
measure 1*50 metres, and their contiguity forms the car. 
The sides of these cubes are made rigid by steel wire 
diagonals fitted with stretchers. The central part of the 
car has a height of 2 metres; its total length is 28 

The steering rudder is carried at the stem; it is 
double, and its surfitce is about 1 5 square metres. It is 
composed of rubber fabric stretched upon a steel tube 
framework having its axis connected to the car by means 
of a cardan joint. The fourth knot of the lifting ropes 
(that of the stern) and two stretchers serve to hold it. 

The '' stabilisator," or elevating rudder, fitted to the 
front of the car, is in reality a " triplane " turning about 
a horizontal axis and able to be inclined from 16 to 17 
degrees above or below the horizontal. Its efficiency is 
considerable, inasmuch as in accordance with specific 
calculations, when the machine is at full speed, the 
effect of the stabilisator is more or less equivalent to 
100 kilogrammes of ballast, according to the degree of 
upward or downward inclination. This rudder, and that 
at the stern, are controlled through steel wires and 
chains, by two wheels placed upon the bridge on the 
right and left respectively; like those of motor-can 
these wheels are " irreversible." 

In the centre of the car is the passengers' acconunodft- 
tion as well as the pilot's position. The latter, hj 
raising the floor of the car, is elevated about 50 cent!* 
metres. The pilot, standing on the left, has the steering 


wheel under his hand ; on his right is his assistant 
holding the elevating rudder-wheel. In front is the 
motor room, and the pilot can communicate direct with 
the engineer. A vertical panel on the front of the 
bridge x^urries the whole of the controlling instruments. 
These are the manometer of the halloon and air- 
ballonnet; the barometer to indicate continuously the 
altitude, as well as a barograph ; the dynamometer which 
permanently records the tractive effort of the screw; 
and lastly, the speedometer registering the number of 
revolutions per minute made by the motor. In addition 
to this is a shelf carrying the chart and a compass, 
well compensated owing to the masses of iron and steel 
in the balloon, to set forth the coiu^se to be followed. 
Through the passengers' space extends a large suspended 
table carrying the road maps, indispensable to the voyage 
and for guidance by comparison with the country 
spread immediately below. Lastly under the car are 
the '^ skates " which enable the airship to alight without 
the car being injured by rubbing against the ground. 

The engine is an explosion motor, such as are used in 
automobiles. It is multicylindrical, works with a 
mixture of air and petrol gas, and is of 105 horse-power. 
The special materials of which it is constructed ensures 
at one and the same time great soHdity and a remarkable 
regularity in running, without forfeiting that lightness 
indispensable to an aeronautical motor. It weighs 352 
kilogrammes aU told. The weight of the petrol tanks is 
64 kilogrammes, that of the oil reservoirs 10 kilo- 
grammes ; the motor is water-cooled ; 65 litres of water 
being carried in a radiator and a circulating system 
which complete weighs 83 kilogrammes. In "working 


order " the total weight, everything included, represents 
5 kilogrammes per horse-power. 

The engine nms at 1050 revolutions per minute, but 
by means of a reducing-system of two gear wheels, the 
propeller shaft does not turn at more than a third of this 
speed — 350 revolutions. The fuel consumption is from 
38 to 40 litres per hour; of oil about 5 litres. The 
whole of the motor is mounted upon a chassis, fixed to 
the car by springs in such a manner that vibration is 
reduced to the minimum, being no greater than in a well- 
built motor-car standing still with the motor running. 
The connection by circular segments is fitted. with 
springs which can be easily regulated by means of a 
worm wheel so as to obtain a constant and absolutely 
certain tightening. Lastly, we may add that the motor 
is fitted with two ignitions, magneto and accumulators, 
and that by means of decompression cocks it can be 
started up with the greatest ease. 


The screw is the propeller exclusively used to-day in 
aerial navigation, both upon dirigibles and aeroplanes. 
As a matter of fact, the screw essentially presents to the 
fullest degree the first and most important acquisition ; 
simple, and when its design, dimensions, and its operation 
are well thought out, its performance is excellent. 

It is scarcely necessary to explain what a propeller is : 
It is a screw y or rather, there are two elements of the 
threads of this screw which we call the vniigs or blades 
which screw into the air. If the screw penetrates wood 
or a metal nut, with each revolution it will advance a 


lertain distance, which is always the same, known as 
he *' pitch," and which is no more than the distance 
leparating two consecutive threads, this distance being 
imputed parallel to the axis. But the screw of an 
kirship screws into the air, and the latter is, for a screw, 
\n essentially unsteady nut, so that at each revolution 
;he aerial vessel, instead of advancing a distance equal to 
he "pitch," only moves forward a part thereof The 
iifFerence between the "pitch" of the screw and the 
idvance of the airship itself for each of these revolutions, 
8 defined as the slip of the screw, that is the proportion 
)f this difference and the " pitch " itself Thus a screw 
may have a slip of ^ if, when it makes a revolution, 
the airship which it drives does not move forward more 
bhan ^ of its pitch. 

This knowledge of slip enables us to consider the 
controversial question of large screws turning slowly, or 
3f small screws revolving very rapidly, and we may easily 
imderstand that it is necessary, a priori, to reject the 
Skarews which are too small : turning very rapidly they 
would begin to drive away the air from around them 
without forcing the airship forward ; their enormous slip 
would not enable it to advance. It is what Colonel 
Renard expressed in a picturesque manner by saying 
"We cannot propel an Atlantic liner by rowing, even 
very rapidly, with a penholder." Let us therefore take 
screws of large diameter. However, one is limited in 
their dimensions by their weight. As they turn power- 
fulfy but slowly, it is necessary to add to their weight 
that of the speed-reducing gear, which transmits the 
always very rapid revolutions of the light motors used in 
aerostation. There will be consequently an absolute 


limit to bear in mind, because it is necessary to choose 
between the efficiency of the propeller, that is to say the 
portion of motor effort which is transformed into useful 
tractive effort, and the engine-power. By augmenting 
the weight of the screws the efficiency of the propeller 
may be improved ; but then it becomes necessary to 
increase the weight of the motor, and it must not be 
forgotten that in aeronautics the question of weight is 
always vital, and that in an airship only a total given 
weight is available for the whole of its mechanical equip- 
ment, motor and propeller. 

One other question now remains — ^the position of the 
propeller ; should it be placed at the prow, at the stem, 
or in the centre? We have already discussed this 
question (p. 43) as well as that of determining the level 
at which it must be driven between the axes of the 
balloon and the car respectively. 

These principles being disposed of we will consider the 
propeller of the CUment-Bayard. 

Hitherto the screws of dirigibles have been made 
of sheets of light metal, or bent upon metal frames; 
sometimes they were even made of fabric stretched over 
a clumsy skeleton. The screw of the ClSment-Bayard is 
of wood, and is a striking piece of work by Chauvi^re the 

It has only two blades ; as a matter of fact if the 
number of the latter were increased too greatly, each 
would move upon the air already displaced by its neigh- 
bour, and efficiency would be decreased. M. Chauvifere 
thought it possible, by special arrangements, to balance 
the efforts of propulsion and the effects of centrifugal 
force arising from the rotary movement, efforts and 


effects which increase in a general manner pretty well 
in accordance with the same laws. 

The Clement-Bayard screw is 5 metres in diameter. 
The pitch is variable and increases from the axis to the 
extremity of the blades. It is built up of countersunk 
ribs assembled and superposed in the form of a fan, 
similar to the steps of a ^* winding staircase." Revolving 
at 350 revolutions per minute, each of the tips of the 
blades describes, in a circular path, 100 metres per 
second, This enormous "peripheral speed" is the 
maximum that has as yet been attained with screws of 
this design. At this speed it produces stabilisating effects, 
called gyroscopic, recalling to mind those of the small 
device used as a toy known as the gyroscope, the stability 
of which, occasionally, is disconcerting ; it seems to defy 
the laws of balance by simultaneously maintaining its 
rotating speed and the mass disposed around its circum- 
ference. In the case of the actual screw its gyroscopic 
effects strongly oppose the pitching of the balloon, and 
produce a stabilisating effect. This was the reason why 
the constructor did not strive too much after lightness in 
the screw, which weighs 90 kilogrammes. 

At speeds of 350 revolutions per minute the Clement- 
Bayard propeUer sustains with its blades a centrifugal 
effort exceeding 19,000 kilogrammes, and yet so perfect 
is its construction that it is not submitted to more than 
one-twentieth of its breaking strain. 

The independent speed of the balloon, driven by its 
motor and propeller, is 50 kilometres per hour; i.e., 14 
metres per second. To complete our description let us 
add that the dirigible is always berthed in a *' hangar," 
which enables it to await, sheltered from heavy weather, 


favourable conditions for the pending journeys. This 
shed is at Sartrouville, but a new shelter is being built 
on the manoeuvring ground at Issy-les-Moulineaux. 


The handling of a dirigible balloon is not so simple as 
that of a spherical balloon owing to the elongated form 
of the envelope containing the gas, and upon which 
depends the ascensional effort. 

The dirigible must at first be brought out of its 
" hangar," wherein it is held upon the ground by a con- 
siderable, imposed weight, comprising bags of ballast. A 
number of men draw up in two lines on each side of the 
balloon, in which the pilot and his assistant take their 
places. The men detach the ballast-bags carefully until 
the balloon evinces a very slight tendency to lift itself; 
hauling with all their might they bring it out of its 
dock, so holding it that it almost touches the ground. 
Arriving in the open air it is hauled to as level an area 
of ground as possible, and then again surcharged with 
the bags of ballast, so that it rests naturally upon the 

The pilot assures himself that all is in good order; 
that the valves work, that the cords which control them 
are to hand, are not twisted or swollen; that the 
recording instruments work properly ; that the wheels of 
the steering rudder and stabilisator efficiently govern 
those two mechanisms; that his compass, his charts, 
his ballast are all to hand, as well as the cord which 
operates the ripping valve. Meantime the engineer has 
passed as minutely over his motor, seeing to the lubrica- 




H I 




tion of all parts, the propeller shaft and screw bearings ; 

tests his indicators and recording instruments, and when 

all is ready informs the pilot. 

The latter now instructs the men to swing the balloon 
rouod in such a way that it starts out "to leeward." 
The passengers are embarked, and the ballast little by 
little discharged, until the balloon slightly rises; this 
operation is called " weighing " the balloon. The pilot 
CDmmapds the engineer to start up the motor, but 
without coupling the propeller- When the engine is 
under way and all is ready he throws out the last bags 
of ballast so as to give the balloon the requisite lifting 
effort. "Hands off," he shouts. At this word the 
workmen let go the sides of the car to which they have 
been clinging, and the balloon is now held by two ropes 
Oily, attached to the under side of the car by a " goose- 
foot" at front and rear. These cords are then " paid 
out" equally, in such a manner as to keep the airship 
horizontal, and when at last the pilot cries "let go," the 
men drop these ropes and the vessel rises. The pilot 
orders the engineer to let in the propeller ; the balloon 
obtains its independent speed, and with a turn to make 
wre the steering mechanism is working properly, sets 
the course it is proposed to take. 

En route, if the weather is clear, the pilot always 
keeps bis eye upon the chart, so as to assure himself 
^t he is following the right course by comparison with 
the actual topography of the country unrolled beneath 
the feet of the travellers. If he ventures out at night 
or in a fog he will fix his attention upon the compass, 
*hile his assistant at the wheel of the elevating rudder 
*ill not let his eye leave the barometer, so as to preserve 


by the manipulation of the rudder, the desired altitude 
of the balloon, without throwing out ballast or letting 
out ga& 

With regard to the sensation of *^wind'' felt by 
travellers, this is only that due to the independent 
speed of the balloon, 45 to 50 kilometres per hour; 
whether it be a following or a head wind it will always 
be the same, neither more nor less intense, because the 
^* surrounding ** wind does nothing but carry the whole 
of the atmosphere, of which the balloon is a part, from 
one point of the earth to another, and travellers in the 
car are under the same condition as if they ran very 
quickly to and fro through the interior of a large ship. 
The speed of their movement would cause them to feel 
an impression of wind which would be the same, irre- 
spective of the direction and force of the wind, which 
blowing over the surface of the sea transports, in a com- 
bined movement, both them and the vessel in which 
they were sheltered. 

So far as concerns ascent and descent, this is effected 
within a small limit of about 100 metres by the manipu- 
lation of the stabilisator. It must be pointed out that, 
unlike the free balloon, the ascensional effort of an 
airship is constantly increasing. Unballasting is con- 
tinuously taking place by the consumption of the petrol 
by the motor, and in this manner it loses about 40 kilo- 
grammes per hour. This is where the charging of the 
air ballonnet fortunately intervenes to secure the con- 
stancy of the external shape and consequently also the 
constancy of the air pressure. 

It is hardly necessary to urge passengers in a dirigible 
to exercise the greatest prudence. Nothing mv^t be 


iroim overboard, be it a bottle, an empty box, or even 

chicken boae, without the pilot's permission : the 

iatic sensibility of these airships is extreme, and it is 

no. 36. Oomtrootor Snraonfi DWtbod of "mooring" a dlrlfible 

r to avoid any action which might vary it acci- 

As to the descent of an airship, at least in the majority 
r cases, it must take place only in a locality where a 
Dcking " hangar " can be obtained, descent in open 
nm^ being always hazardous. This was only too well 
lown in the accidents to the Patrie and the Zeppelin. 
Atifltng ia made in a manner just opposite to that of 
soent. But care must be observed that the men who 


seize the two guide-ropes to bring the balloon gently to 
earthy at first grasp the " windward " rope so as to hold 
the balloon with its nose to the wind ; negligence of this 
precaution, the balloon^ held only by the stem rope^ 
would rear up, owing to the wind driving against the 
prow, and thus imperil it. Once the balloon has landed 
the workmen seize it by the car, keep it down by attach- 
ing numerous bags of ballast, and then bear it gently 
into its hangar. 

It might however reach, and be compelled to descend, 
in open country, and to " moor " by fixing the airship 
with its anchors. In this case there is an arrangement 
conceived by M. Surcouf which appears to offer the 
greatest security to the airship forced to make a *^ halt " 
at a place unprovided with a special shelter. 

Beneath the body, and towards the front of the 
balloon leading to the ballonnet, is an automatic valve 
(Fig. 25) which can open itself like a purse. During 
the journey a spring keeps it closed, and the ballonnet 
works as usual by means of its charging fan. But if 
the vessel is compelled to stop, it is fixed to the ground 
by anchors, or by stakes, with the cable, which by 
means of a " goose foot " is attached to the prow of the 
car, the balloon thus being held stationary, with its motor 
stopped, swinging in the wind. But under the influence 
of temperature changes the gas will contract or expand, 
and with the motor no longer running, the ballonnet 
will not be able to maintain the invariable form of the 

Then, under the pulling action of the same restraining 
cords, the " mooring " valve opens, always to the wind, 
since it is to the front of the balloon, the latter adapting 


itself like a weather vane, nose to the wind. Under 
these conditions the air so caught in the pocket hlows it 
open, and keeps the ballonnet inflated to assure the 
permanency of its shape. One can, for greater security, 
attach bags of ballast to the stern rope. If the stern of 
the balloon should descend this ballast would strike the 
ground, and the envelope, released of a considerable 
weight, would rise again before it could come into con- 
tact with the earth and thereby be damaged. 


The dirigible balloon which we will describe in detail 
has completed more than thirty trips, with uniform 
success. During the Aeronautical] Show held at the 
Grand Palais in the month of December 1908, it 
repeatedly came and hovered above the Champs- Elysees. 
Its evolutions above Paris have rendered it popular, 
acquainting the whole population with the appearance 
and travel of an airship. It has made numerous cruises 
around the capital, some very long, all brilliant, first 
under the direction of M. Kapf(Srer, collaborator of 
IL Surcouf ; later of M. Gapazza, the eminent Corsican 
aeronaut, who so far has been the ,only one to accom- 
plish the crossing of the Mediterranean in a balloon. 

The most remarkable of these excursions was that 
when M. Clement resolved to set out from the airship 
** hangar'' to visit his seat at Pierrefonds (Fig. 26). The 
vessel left Sartrouville on November 1 at 11.15 a.m. in a 
east-south-east wind blowing at a velocity of 20 
kilometres per hour. M. Clement, the owner of the 
balloon, was accompanied by a passenger ; MM. Capazza 


and Kapf^rer were on the bridge ; Sabatier the rai^eer, 
and a mechauician, were at the motor. The balloon 
passed successively over Maisons-Lafitte, Pierrelaye, 
I'isle-Adam, Beaumont, Crell (at 12.30), Font S^ta- 
Max^nce, Compifegne (at 1.30). It then wore round to 

FlO. 26. Vojage of the " CWmeot- Bayard " (Novsmlwr 1908), (S60 k 
in a ctoeed circle in five houn without dewwat) 

the east and arrived at Pierrefonds at two o'clock ; tboD 
it resumed its journey to Paris, by Rocquemont, 
Ermenonville, Chennevi^res, Bourget (passed at 3.30), 
Pantin ; then described a large circular sweep overParia, 
and regained Sartrouville at eight minutes past four. 
The total distance was 200 kilometres, and it was 


covered in 4 hours 50 minutes. It was the " world's 
lecord" for a round trip accomplished by a dirigible 
without descent during its journey, and returning to its 
starting-point. The great journey of the Zeppelin^ of 
which we shall speak in the following chapter, was not 
completed by return to the point of departure, inasmuch 
M the MTship was unfortunately destroyed in the course 
of its homeward journey. 
Here is the airship's official ^' bill off lading " : 6 


psSBongers, 300 litres of fuel, 20 litres of oil, 65 litres of 
water, 250 kilogrammes of ballast (sand in bags), and 59 
kilogrammes of manoeuvring ropes. 


A dirigible such as we have described is, in the field of 
aerial navigation, the equivalent of a warship, or of a 
large mercantile steamship; it is the "ocean liner." 
Bat its great cost (about £12,000) the absolute necessity 
j> of maintaining an immense and expensive hangar in 
* which to dock it, renders it a vessel of pleasure inacces- 
riUe to many amateurs for aerial trips. There had to 
be devised the ** little dirigible," the ^' aerial yacht " at 
a more popular price, and more simple to control. This 
very convenient type of small balloon is available to-day, 
and is known under the generic name of the '^ Zodiac/' 

ThiSy to hazard a comparison borrowed from auto- 

mobilism, is the " aerial voiturette." It is designed to 

/ eoahle one or two passengers to make easy trips into the 

mr, and without the necessity of maintaining a sheltering 

For this purpose the gas bag, of 700 cubic metres, is 




iuflated not with pure hjdrogen, which is expensive and 
not always obtainable, but with coal ^s which is avail- 
able at all towns and can be purchased cheaply. Inflated 
therewith it will lift one pereon, but by combining about 
100 cubic metres of hydrogen, it will lift two. It is 

PiO. 27. A little "Zodiu" dlrigtblo 

pisciform in shape, with stabilisating planes, and Has two 

The car is detachable into three pieces ; each of than 
is formed of wooden trellis, light, flexible, and yet at the 
same time solid, being fixed together by bronze Bockets, 
nuts, and bolts. A water-cooled, four-cylinder, 16 honft- 
power motor drives through cardan shafting a stern 
screw, which runs at about 600 revolutions per minute; 
the latter is of 2*30 metres diameter. The motor 
actuates also a fen which may be seen inthephotograjdt; 
this keeps, through the medium of an ajr-ballonnet, the 
permanent external form of the envelope. 

The whole balloon dismantled, car and envelope, 
packed in canvas cloth, can be transported by horse and 
cart. One inflates the balloon at the spot where the 

THE N-/ __ 




gas is obtainable, and it can be prepared for an ascent 
in an hour and a half. The little airship can travel at 
a speed ranging from 25 to 28 kilometres per hour ; can 
remain aloft for three hours with 75 kilogrammes of 
ballast, and costs ready for use £1000. Truly therefore 
it is the aerial "auto/' enabling trips to be made in 
the air without being compelled to return to a stationary 
hanganr^ because the balloon coming to earth at the end 
of its journey can be deflated like a simple '' spherical " and 
loaded upon a cart for conveyance to the nearest station. 
This handy type of little dirigible certainly fulfils in 
every respect the " airship for alL" On Easter Sunday, 
April 11, 1909, it made a remarkable journey. With 
MM. Henry de la Vaulx and Clerget on board, it 
mancBuvred above the Bois de Boulogne for three hours 
with the greatest ease, before the eyes of crowds of 
Parisians, which the beautiful weather had caused to 
flock upon their favourite promenade. 


And now, a question which will naturally arise in the 
mind of the reader, a question which is prompted to all 
those who have travelled in a dirigible. What are one's 
sensations ? Does one sufier from giddiness ? Has one 
8ea-sicknes8 ? Has one fear ? 
I will endeavour to reply to these interrogations. 
On board one has a feeling of complete security. 
Before entering the car there is time to take a walk 
tt)iind the balloon, for it is still berthed in its dock ; to 
examine with care every part, feel the lifting and sus- 
pension system. The whole is so solid ; is made of 


material of such perfect quality ; the total reBistance is 
80 well calculated and tested to twenty times what the 
whole will have to withstand, that in an instant every 
qualm of disquietude slips from the mind : the only 
hesitation one has is that of actually embarking. But 
the catastrophes of the Pax and the Bradsky balloon 
have been instructive. To-day the general utilisation of 
the air ballonnet secures stability ; the motor is placed 
well away from the balloon ; the suspension system 
is indeformable and distributes the weight equally over 
the envelope ; all parts of the motor capable of giving 
off either sparks or leakages of gas are boxed m 
or covered with metallic sheathing : lastly, trained 
and experienced aeronauts always conduct the ascentB, 
for no owner of an airship would be mad enough to 
attempt a trip without the indispensable assistance of 
one of those ** captains of the air " such as, for example, 
the Count de la Yaulx, Capazza, or Eapf($rer. 

Mal'de-mer is unknown aboard these airships, for the 
simple reason that the longitudinal stability being so 
very great there is neither pitching nor rolling. Many 
are the ladies who have already received the baptism of 
the air ; not one of them has suffered from this terrible 
malady of which ocean vessels preserve, alas ! the un- 
enviable monopoly. 

With regard to dizziness this is unknown in a balloon 
when the latter is not held to the earth by a rope. 
Dizziness, when looking from the height of a tower or 
from the edge of a precipice, is produced by the view of 
the vertical wall which drops below one's self, and which 
" conducting the eye " right down to the bottom, enables 
one to calculate the depth of the chasm. In the captive 


balloon the sight of the cable may Bometimes produce 
the same effect; but in a dirigible, there being no 
material connection, one cannot estimate one's altitude : 
one believes, and one actually is, above a magnificent 
plan in relief, with the feeling of beatitude which is 
grand, with the impression of mdeed being independent 
of aU, to have broken away firom one's bonds and to be 
the master of space. 

One can now consequently accomplish by dirigible 
and with absolute safety, voyages in the strictest sense 
of the word. I have made many myself, which I will 
never forget, on board the CUment-Bayard. The time 
is not far distant when airships, in addition to their 
military utilisation, of which we will speak after we have 
described aviation apparatuses, will have applications to 
everyday life, without speaking of their employment, 
which will arise, for those geographical explorations 
which yet remain to be made. 



Early days of aeronautics: From General Mbusnier to 
Colonel Renard^ Giffard^ Dupuy de L^me, Tusandier : M. 
Henry Deutsch^ Count Zeppelin, M. Santos-Dumont and 

M. Lebaudy 


The history of dirigible balloons, up to recent times, has 
been somewhat devoid of results. If the importance of 
what has been done is unquestionable, it can at least be 
asserted that the quality in this case substitutes quantity, 
since it was no farther back than 1852 that the first 
serious attempt in this direction was made by Henry 
Oiffard. Before him there may have been some ideas 
more or less vague, but nothing tangible. 

However, it is one of these projects which it is neces- 
sary to describe, and that v^ith some detail, because of 
its importance, its far-reaching value, and the date of its 
conception. It is that made in 1784, scarcely one year 
after the discovery of the brothers Montgolfier, by an 
engineering officer — Lieutenant, subsequently, General 

Meusnier was an extraordinary intellect. He aston- 
ished his masters by his precocity, by the confidence of 
his reasoning, by the perspicacity of his views. He was 



a member of the Acad^mie des Sciences at twenty-nine, 
after his work in aerostation, which however was only 
one of his accomplishments, and he was the collaborator 
of Lavoisier in several experiments. He was killed at 
the siege of Mayence in 1793 ; he was then General. 

Meusnier was the true inventor of aerial navigation, 
and was a ** scientific " initiator. Through not following 
the lines which he laid down, aerial navigation lost a 
century in futile groping about ; in experiments abso- 
lutely without method. In fact, at a time when 
relatively nothing was known concerning the science of 
the atniosphere, Meusniei: had the distinction of finding 
in one stroke all the laws governing the stability of an 
airship, and calculating the conditions of equilibrium for 
an elongated balloon, after having strikingly demon- 
strated the necessity of this elongation. Meusnier's 
designs and calculations are preserved in the technical 
engineering section at the French War Office in the form 
of drawings and numerical tables . 

His airship designs relate to two balloons, one very 
large, the other much smaller, and it is in these projects 
that one finds distinctly described two absolutely new 
arrangements which are in universal use to-day : the 
cUr-bcdlonnet to secure stability and the screw for aerial 
propulsion. With regard to the motive power, owing 
to the absence of suitable motors in his day, he contented 
himself with the use of the muscular power of the men 
carried on board. 

The dimensions of his largest balloon (which however 
was never constructed) were 260 feet in length, and 130 
feet in diameter ; that is to say 85 and i2*50 metres 
respectively. The shape was that of an ellipse, and as 


one may see, the elongation was equal to twice the 
diameter. The cubical contents were to be 60,000 cubic 

The balloon (Fig. 28) would thus have followed the 
form of a perfect ellipsoid, which was the paramount 
development to be realised as compared with the sphe- 
rical form. It was to be a double envelope, comprising 
two skins, each of which was to fulfil a different 
purpose. The first, the " envelope of strength," very 
resistant, was consolidated by bands. The second, 
placed within the former, was to be impermeable to the 
light gas which was to sustain it. This inner balloon 
was never to be completely inflated and the space 
between the two envelopes was to receive, in varying 
quantities, the air to be forced therein through pipes by 
two pumps carried in the car. This was in very truth the 
air-ballonnetf and its use was certainly to maintain invari- 
ability of the exterior form. 

The car was attached to the envelopes by a triangular 
suspension system. This was the '* indeformable sus- 
pension " which is to-day considered imperative, and 
which is universally adopted. The lifting system was 
to be attached not to a net, but to a girth sewn to the 
fabric. Moreover, at three points where the lifting 
rope members met, forming " suspension knots," were 
fitted the axes of the three propellers, that Meusnier 
described as " revolving oars " (rames toumantes) and 
which were no other than screw propellers. Conse- 
quently this remarkable system, which is universally 
used to-day for driving steamships, was invented in 
1784 for aerial navigation and by a Frenchman at that. 
But that was not all. Meusnier not only recomimended 


the elongated form ; not only conceived the girth fasten- 
ing ; the triangular suspension ; the air ballonnet ; and 
screw propeller ; but moreover indicated the point the 
latter should be installed. It may be observed in the 

^,„^) 1 ' 


-XV /' '^""i » 


/: yj^^"""^^^^^^^^ \ \ II 

\^:>-%pe tarfd from which 

car is suspendWL^i^/ 


■^=#^ j^/ 

Stern \^ \|\^ ^l/")^^ J* // ■""" 

mf#Air pipes. 

Rudder ^^^^^^^ 


Pie. S8. Dedffn for the flnt dirigible b; Oenenl Uetunler (17S4) 

diagram that the motor shaft is not connected to the 
car, but is placed between this latter and the balloon. 
In this way the illustrious and accomplished officer 
Bet forth in one stroke everything requisite for aerial 
navigation. For this reason he justly deserves the 
distinction of being the forerunner, the initiator, of 

We are indebted for this information to a remarkable 


memoir of the engineering lieutenant Ldtoum^, which 
was presented to the Acad^mie des Sciences by General 
Perrier in 1886, wherein these details are set forth in a 
very scientific manner. 

AIRSHIP (1852) 

It was some sixty years later that the solution was first 
practically resolved, by an eminent engineer whose name 
is justly celebrated — Henry GiffiBuxl, the inventor of the 
*' Oiffitrd injector," used throughout the world in con- 
nection with the boilers of locomotives. Giffiird was 
convinced of the impotency of the '* human motor/' and its 
excessive weight, and he conceived the audacious project 
of carrying under an elongated balloon, a steam-engine 
complete with boiler and propeller. One shudders in 
thinking of the courage of this man in venturing to carry 
an incandescent fire inunediately beneath his balloon 
inflated with hydrogen. But the many precautions which 
he adopted ensured him of safety. 

The shape of his balloon was of a symmetrical cigar, 
pointed at both ends (Fig. 29). Its length was 44 metres, 
diameter 12 metres, the elongation thus being in the 
proportion of 3 '5. Its volume was 2500 cubic metres, 
and it was inflated with coal-gas which gave him a lifting 
power of 1200 kilogrammes. The steam-engine, including 
boiler, weighed 159 kilogrammes, and developed 3 horse- 
power,giving a weight of 53 kilogrammes per horse-power. 
It was at that time a noteworthy achievement. The 
engine was inverted, to reduce the risks from fire, and 
was mounted on a platform attached by six ropes to a 
" strengthened beam " supported by slings connected to 



a net which corered the whole of the balloon except on 
its under side. This suspension, one can see, had the 
drawback of being possible of displacement. Moreover, 
the absence of the ballonnet did not secure permanence 
of the envelope's exterior form. On the other hand, the 

Fro. 39. Btnij aiBard't atsam-driTen tMlloon (ISS2) 

use of the long pole had the advantage of distributing, in 
a pretty uniform manner, the strain upon the whole of 
the aerostatic envelope. At the stern a triangular Bail, 
mancBUvred firom the car, formed the rudder. 

With this balloon Giffard carried out eome experiments 
of the greatest value. True, the low independent speed 
(3 metres per second) which he obtained, in conformity 
with his calculations, did not permit him to navigate in 
the air in a circle : that is to iulfit an " aerial voyage " ; 


but he was able to make some very neat evolutions, 
deviating at his desire from the direction of the vrind, 
thereby testifying to the efficiency of his rudder. In a 
word, he succeeded in demonstrating, in an experimental 
and unquestionable manner, the possibility of aerial navi- 
gation by the aid of an airship furnished with a motor 
and a screw. His efforts justly belong, consequently, to 
the history of aeronautics. 


It is necessary to wait another twenty years to see a 
second rational effort in aerial navigation. This was that 
made by the illustrious marine engineer, Dupuy de Ldme, 
the inventor of the ironclad. Struck with the value of 
balloons during the siege of Paris, Dupuy de Ldme 
thought that this usefulness could be doubled if one 
were able, not only to leave the besieged capital as did 
the free balloons, but to return again at will ! So he set 
to work to perfect a dirigible free from the disadvajitages 
of Giffard's. 

Notwithstanding the excessive weight of the human 
motor, he decided to rely upon the muscular energy 
of the passengers to move his screw, so as to avoid 
the dangers of the steam-engine. The balloon was 
fusiform, symmetrical, and pointed at both ends. Its 
length was 36*50 metres, diameter 14*84 metres, giving 
an elongation equivalent to 2*5. The volume of the 
envelope was 3450 cubic metres. 

In the interior of the latter was placed an air-hallonnet ; 
this, in short, was the first time that Meusnier's concep- 
tion was realised. The volume of this ballonnet was a 


tenth of that of the ballooD. Dupuy de L6m6 did not 
pin his faith, in the use of the ballonnet, to the lines 
set forth by Greneral Meusnier: he adopted the inde- 
formable triangular network suspension. The screw 
weighed 75 kilogrammes, was 9 metres in diameter, and 
was driven by eight men. Under these conditions the 
stability was perfect/and in still air the balloon was able 
to travel at a speed of 2*25 metres per second — very 
nearly 8 kilometres per hour. 

Conceived and calculated during the siege of Paris, the 
balloon was not built until 1872. It did no more than 
start at Vincennes, on February 2, 1872. Notwithstand- 
ing a violent wind, the stability was perfect, owing to the 
triangular suspension, and the airship was able to deviate 
12 degrees from the wind's direction. This test had 
the merit of defining the essential points for the con- 
struction of dirigibles, and to show the possibility of 
obtaining, while travelling, an absolutely perfect stability. 

nSSANDIER (1883) 

Impressed by the qualities and regular working of 
the electric motor, and the absence of danger which 
attended its use, MM. Albert and Gaston Tissandier 
built, in 1883, a dirigible airship driven by an electric 
motor, for which the energy was supplied from a 
bichromate of potash pile battery. 

The balloon, properly so-called, was fusiform, sym- 
metrical, with the two ends pointed, and having an 
elongation equal to 3 ; its length was 28 metres, 
greatest diameter 9*2 metres, and its volume 1060 
cubic metres. The netting, the cords and the knots 


of which, by their projection, offered such resistance 
to movement, was replaced by a suspension*' cover." 
The very light screw weighed no more than 7 kilogrammes, 
and was set 10 metres firom the balloon. 

The motor (a Siemens dynamo) weighed 55 kilogrammes 
for a motive effort of 1^ horse-power ; the electricity was 
furnished by four batteries, of which each comprised ox 
compartments, each forming a pile element. The reser- 
voirs, raised or lowered at will by a sjrstem of pulleys, 
connected or disconnected the liquid exciter, which was 
an acid solution of bichromate of potash. 

After a preliminary trip in October 1883, the balkmi, 
in September 1884, sailed for so long as two hours at an 
independent speed of 4 metres per second : it was not 
able to go against the wind, but was able to complete 
numerous evolutions to the right or lefl of the direction 
of the latter. Stability was defective, owing to the 
absence of the ballonnet. 

Be that as it may, the Tissandier balloon was the first 
dirigible driven by electricity ; it opened a way which 
could be followed, and which might lead towards the 
definite solution of the problem of aerial navigation. 

"LA FRANCE" (1884 AND 1885) 

It was at this time that Captain Renard, director of the 
military aeronautictvl establishment at Chalais-Meudon, in 
collaboration with Captain Krebs, and his brother, Captain 
Paul Kenard, built a vessel which combined in its un- 
precedented type all indispensable features, and which 
realised all necessary requirements as much in the 
aerostatical as in the mechanical parts. This balloon is 


indisputably the starting-point of practical aerial navi- 
gation, and it has served aa a model to all that have 
Ebllowed. Moreover, those who have digressed from the 
leasoDB furnished thereby have coimted nothing else but 
This pisciform ballooQ (Fig. 30), with its larger end in 

Fia. so. "fff'T B«iiard ftod Erebt' ImIIooii La Fnttut (ISM) 

froat, was 51 metres long and 8 '40 metres in maximum 
diameter, which represents an elongation equal to 6. Its 
Tolome was 1864 cubic melres. The envelope, of varnished 
Chinese silk, was built up of longitudinal gores converging 
tanmids the two points. The network was replaced by a 
" cover " formed of bands of transversal widths of silk 
Mini tt^ther at their edges, and so cut out as to follow 
the " geodesical lines " of the surface. The triangular 
■D^iension advocated by Dupuy de L6me was discarded 
is &vour of two oblique " cross-pieces " connecting with 
tke frtmt and rear of the car, and with the balloon cover 
SDi^wDfflOn ; those in the centre were parallel with them, 
and directly carried the car. 


The vertical steering rudder was placed at the stem. 
It was a lath framework strengthened by two diagonals, 
and covered with a double sheathing of silk stretched to 
form its surface. At the rear of the car, moving about a 
horizontal axis, was an ** elevating rudder " which inclined 
to the front or to the rear, enabling the balloon to be given 
an ascending or descending movement. 

The design of the car was a completely new idea ; its 
great length recalled the oar-propelled yawls used in 
regattas. It was built up of bamboo trellis, had a length 
of 32 metres by 1 '30 metres broad, and a maximum depth 
of 1*80 metres. Its great length is copied to-day in the 
most successful dirigibles, such as the FiUe de Paris and 
the CUment'Baya/rd. A " cabin,** coni^aining the motor 
and all necessary control, was placed forward* 

The motor, built by M. Granune, weighed 96 kilo- 
grammes, and developed 9 horse-power. The energy was 
transmitted through a hollow shaft, the bearings of 
which were fixed to two flexible suspensions, to a screw 
placed at the prow of the vessel. This arrangement is 
likewise copied to-day in our most modern dirigibles. 
The screw was 7 metres in diameter, with a pitch of 8*50 
metres, and weighed 40 kilogrammes : it made 50 
revolutions per minute. 

The electrical generator comprised a "chromium 
chloride " battery invented by Colonel Benard and was 
of extreme lightness. Each element was formed of a 
glass tube in which was a very thin platinum-silver ^ 
electrode, in the centre of which was a zinc rod. ' 
The total weight of this accumulator was 400 kilo- j 
grammes, which represented 44 kilogrammes per horse- i 


e independent speed of the airship with this motive 
m was 6'50 metres per second, 
e first ascent took place at Chalais on September 1 2, 
. The balloon manoeuvred with the greatest ease 
"etumed under its own power to the starting-point. 

St Cloud // 

Boulogne / 


a/k I s 

M //" 









Sevres \ 




t^jBuratpr nia^e 




Srpl S3 1885 

jf ^Meudon 


m mJeuney laade 

iS? * 



>. SI. The Bnt two Mrial TOjagM in • doMd circle mmde by La Frane», 
OT«r PiHi, in 1B8S 

was a decided triumph, which echoed throughout 
rwld. Three further ascents were made in the same 
to tune up the apparatus. Then in September 1885 
listorical ascents were held in the presence of General 
lenon, Minister of War. La France lef% Chalais, 
ibed several evolutions over Paris, and returned 
B hangar under its own power : the Jirxt round 


'' aerial voyage " there and hack was accompLxAd 
(Fig. 31) : aerial navigation became an acoomplifihed 
fact, the '* highway of the air " was opened and aeicnaotB 
had only to fly. 


The Chalais-Meudon balloon was consequently tfae 
marvel of its day and undoubtedly with electric moton 
it was difficult to go &rther in this direction ; but a new 
mechanical engine had appeared creating a new industry 
and revolutionising the art of transportation : this wai 
the '' petrol motor." One man contributed as much bf 
his eflbrts and his personal action as by his genero» 
encouragements to popularising its exclusive use for 
aerial navigation. This was M. Henry Deutsch de la ^ 

So soon as it appeared he undertook the important 
task of showing the part the explosion motor was destined 
to fulfil ; it comprised that marvellous accumulator of 
energy — petroleum spirit. From his youth he had been 
consumed by one obsession — the solution of aerial navi- 
gation. When he saw what Colonel Renard had done 
by the use of the electrical motor, he conceived the idea 
of using the petrol engine for aeronautical purposes, and 
as far back as 1887 demonstrated to the officers of 
Meudon the possibilities there were in extending their 
efforts towards this end. At the same time he ordered 
the constructors Mignon and Rouart to build an explosion 
motor upon the new lines, and in 1889, showed President 
Carnot the first petrol motor-driven carriage. Always 
reverting to his idea of steering balloons, he accordingly 


'Undertook to furniEh the financial and materia) means to 
Remonstrate its possibilities, in connection with hie first 
idea : after expending considerable sums in actual 
arch, he unhesitatingly offered numerous prizes to 
IteHcourage the efforts of aeronauts and aviators. The 

Tia. SS. Bonto knd altitude map of Santoa-DumoQt'i jouroej (the OeutMli 
PrUe, Oclolwr 1901) 

** Deutach prize " of £4000 certainly contributed much to 

fttamalate their enthusiasm, and it is only an act of 

Jnetice and acknowledgment to place the name of 

I- "Mi. Henry Deutsch at the forefront of contemporary 

t Aeronautical history, the many conquests in which are 

^ tUkdoubtedlydueto the exclusive use of explosion motors. 

r It was M. Santos-Dumont who, on October 19, 1901, 

L '^voa the Deutsch prize, the conditions of which consisted 

F in setting out from St. Cloud, doubling the Eiffel Tower, 

i And returning to the starting-point within half an hour 

(Fig. 32). With an indomitable perseverance, an unheard- 

' of audacity carried to intrepidity, the young Brazilian 

' aeronaut built dirigible upon diri^ble. some large, some 


small, some medium, and at last, after ten times escaping 
death, he succeeded in carrjring off the much-coveted prize. 
His name became deservedly well known, more especially 
as a little later he lifted the first "Deutsch prize" for avia- 
tion. The airship with which he carried off these trophies, 
the Santos-Dumont No. 6, had an elliptical envelope d 
33 metres length by 6 metres in diameter, and a volume of 
622 cubic metres ; there was an air-ballonnet of 60 cubic 
metres capacity, and his motor developed 16 horse- 

Once the movement in favour of aerial navigation vm 
started, it extended rapidly ; on all sides surged inventors, 
not always alas ! sufficiently proficient in theory ex 
practice ; not always prudent enough ; not always pro- 
fiting by the lessons given by their illustrious predecessora 
The Brazilian Severo d' Albuquerque met his death in 1902 
through his balloon exploding owing to the lack of fore- 
sight in the installation of his motor ; in the course of 
the same year 1902, the engineer Bradsky was killed, 
together with his companion Paul Morin, owing to the 
defective character of the suspension of his dirigible, 
which, notwithstanding Colonel Renard's reconunenda- 
tions, did not include the ballormet. 


These catastrophes did not damp the ardour of the 
aeronauts. But they made them more careful, and led 
them to realise the necessity there was for them to be 
thoroughly grounded in all questions touching aeronautics, 
if they desired to venture to build and test a dirigible. So 
in 1902, when MM. Lebaudy decided upon the construc- 
tion of a huge airship, they secured the collaboration of a 


distinguished engineer, M. JuiUot, and entrusted its erec- 
tion to one of the most skilful " builders " M. Surcouf 


Vertical plane 

Slabihsator frame 

Car a. IVm screws; 

VsrUcal keel, 

Fzo. 8S. The dirigible balloon L$l>audy (side elevation) 

The Lehaudy balloon (Figs. 33 and 34), which the 
Parifiians promptly christened the "Jaune" (yellow) 

Rudiler - 

iVaine of stabilisator 

1 ^rz^T'^m y/yyyyyy^^;:7,'yyyy. 'yyy^ 

— ,^^^»^-^ — 

burtace p^ 
horizjonbal tail An. 

oupporiuig lM^al^. 

FlO. 34. The dirigible balloon Zebaudy (under-side plan) 

owing to the colour produced by the varnish upon the 
eoctemal sm&ce of its envelope, measured 58 metres long 
by 9.80 metres greater diameter : its elongation is conse- 
quently 5.6, and its total volume was 2300 cubic metres. 
It is dissymmetrical, the greatest diameter being forwards 
and is pointed at both ends. The body of the balloon is 


not completely ** round/' the lower part being cut by a 
section thereby fonning a flat plane resting upon sjram 
serving as the suspension medium for the envelope and the 
car. At the same time, the flat form of this firaming acts is 
a " stabilisating plane/' which is efficient in use. Under 
this frame is a "strengthened girder," which, covered 
with &bric, forms a vertical stabilisating plane extended 
into a veritable bird's tail, a stabilisator in itself, and whidi 
is terminated by the steering rudder properly called. 

The car is short, and the motor which is fitted therein 
transmits its power to two screws of 2*44 metres diameter, 
one being three, the other two, bladed. The propelling 
force is exerted therefore not at the extreme front, as in 
the La France, or at the rear as in the Santas DumorU, 
but about amidships. The short length of this car renders 
difficult the uniform distribution of its weight upon the 
envelope : also the latter has a peculiar '* saddle form ; " it 
is hollowed towards its centre in the manner of a saddle, 
due to the weight of the car imposed upon the central 
part of the envelope. This arrangement has its disad- 
vantage in this sense, that the general form of the balloon 
is altered, and does not in practice conform to the princi- 
ples which have served in determining the theoretical 
conditions of equilibrium and of propulsion. It is just to 
add that the efficiency of this balloon is remarkable. The 
air-ballonnet is divided into three compartments, to pre- 
vent the air surging towards the base in case the airship 
becomes tilted, and has a capacity of 500 cubic metres. 
The motor is of the Mercedes pattern, and develops 40 
horse-power when running at 1200 revolutions per minute. 
An acetylene searchlight of 100,000 candle-power, 
mounted with a projector, facilitates landing at night. 

• ■ « 



After a magnificent series of triumphant flights made 
in 1904, MM. Lebaudy in 1905 offered this magnificent 
dirigible to the Minister of War, who sent it to Toul. 
The State then decided to order a dirigible of the same 
" semi-rigid " type ; this was La Patrie. 

Save in some details, La Patrie was identical with the 
Lebaudy : its volume was increased by 200 cubic metres 
through extending the length by 2 metres ; the ballonnet 
was 650 cubic metres instead of 500, and the motor 
built by Panhard and Levassor developed 70 as against 
40 horse-power. Lastly, instead of ending in a point the 
stem was rounded and fitted with a cruciform '' empen- 
nage " for the purpose of securing still greater stability. 
An elevating governor of two projecting planes was fixed 
to the front of the horizontal stabilisating framework. 
Otherwise it was a sister airship to the Lebaudy. 

The life of the Patrie was brilliant but short. After 
it had proved its exceptional qualities such as no other 
airship had shown up to that time, after it had travelled 
under its own power from Paris to Verdun in seven hours 
without any incident on November 23, 1907, this magni- 
ficent dirigible some days after was caught in a gale 
which forced a descent. Despite the efforts of 200 
soldiers the wind catching its enormous broadside surface 
tore the balloon from their hands, and bore it away in the 
storm. It passed over France and England, dropping 
pieces of its motor at different points on English terri- 
tory, and disappeared into the North Sea, where it was 
perceived, still inflated, some days after the accident. 

A new balloon of the same type, the Repuhlique was 
ordered by the Government from MM. Lebaudy for the 
national defence. The JRSpuhlique presents some remark- 



able features : the impennealiilily of ite e tt icl mie per 
mite it to Fomain ixiflated 110 daya inA one cAmge of 
gaa. Ite fint flight, made in September 1908, ksted 
six and a half hoursy and it covered over 200 IdkmetraB 
in a doeed cirda After the CZfaiait-JBoyanI this k 
the moet striking record of a comfJeto tzip without 
descent, and with return to the startii^-pcHnt. The 
characteristics of the Bfyublique are the same as those 
of La Patrie as well as the arrangement of the motor 
and '' empennage." The BSpubUque has been ''mili- 
tarised/' and without a doubt will be employed finr the 
defence of the eastern frontier. Lastly, a new militaiy 
balloon, the LiberU^ mora powerful still, is under oonstnie- 
tion : it will be 67 metres long, of 2400 cuUc metreB 
capacity, and will be'fitted with a 100 horse-power motor. 


All this time M. H. Deutsch de la Meurthe had not 
remained idle. Not content with merely having en- 
couraged aeronautics, he wished to become a militant 
himself: he thereforo had an airship constructed after 
the designs of M. Tatin. This vessel, not giving the 
expected results, he ordered a second in 1906, and for 
this secured M. Surcouf, who had become instilled with 
the ideas of Colonel Renard. For the first time he 
conceived an '' empennage " of inflated ballonnets, which 
we have already described in discussing longitudinal 
stability. The body of the balloon (Fig. 35) is pisciform, 
with the master-diameter towards the front. The stem 
is connected to a cylinder carrying the stabilisating 



hancumrte. Its len^itii k 60*50 we^xes; maximiim 
dkaeter, 10'50 metres; Tofamie, 3200 cubic metres. 
Tike CU-, lftttio&-wark of metal tabmi^ is 30 metres long, 
a&d of tbe " stref^^tbened girder* fiscm. The baUoimet, 
dirided into three fompartmcgta^ las a ridiiiiie of 500 
cable metroB, and t«t> rodders are attached to the car, 
ooe for staering latenllj, and the other fix* aaooit and 
deBoent. The 70 hone-power motor driveB a two-bladed 
propeDer 6 metzee in diameter, ranning at 900 revolu- 
tiona. The aoefw, fdaoed at the prow in oonformity with 
the ideas of Coknd Benard, makes, through a reducing 
gear, 180 rerolntioDS per minute. Tliis huge airship has 
aooomidished soceessfbl flights, and it was cm board this 
vessel that the Prince rf Monaco, the eminent and learned 
navigator, who has surveyed and sounded the ocean, re- 
ceived the ** baptism erf* the air," the highest altitudes of 
which he had previously scientifically explored in mid- 
Atlantic by means of '' sounding balloons.'' 

After the catastrophe which destroyed the Pdtrie^ M. 
Henry Deutsch made a patriotic, generous offer; his 
balloon was ready ; he submitted it to the Minister of 
War to take the place of the lost airship, and the Ville- 
de-Paris set out from Paris to Verdun, under its own 
power, to replace the wrecked dirigible. This voyage 
was made on January 15, 1908 (Fig. 36). 

During the exploits of M. Deutsch's balloon, M. 
Clement, one of our best known automobile builders, 
ordered from M. Surcouf a dirigible of the same type, 
but a little larger — the Bayard. We have already de- 
scribed it in detail, so there is no need to do so again. 
Let us simply say that a new airship, the Ville-de- 
Bordeaux, has recently issued from the Surcouf works, 




i ' ^9 


B) : ,,M 

H' ' '^1^1 

I^V *'( 3^^^^H 


1 - • 


and that its features appear to be in no way inferior to 
i its contemporaries. Finally, another airship of the same 
type, the Colonel Menard, has been ordered by the Govern- 
ment for the national defence. 
Count H. de la Yaulx has built some excellent small 

f^o. 36. Joomey of the VUU-de-Parii from Bartrouyille to Verdun 

(January 16» 1908) 

dirigibles of less cubical capacity with a very ingenious 
arrangement, consisting as we have already explained 
(page 43) in placing the screw between the balloon and 
the car, on a level with an intermediate beam. His 
dirigible, of small volume (720 cubic metres), is very 
ooanageable and has given ezceUent results. 


The attention of our neighbours across the Bhine was 
quickly drawn to the gigantic progress effected in France 
in aeronautical traveL They at once foresaw its military 
applications, and desirous of not being left behind, re- 
solved to excel the French constructors in the building 
of a gigantic airship— ^^ colossal " as it is colloquially called 
in Gennany. It was Count Zeppelin who, with a dogged 
perseverance, an ardent patriotism, which one cannot 
bat admire, concentrated his knowledge, his life, and his 


fortune, to the fulfilment of this idea. Moreover, it was 
shared and sustained not only by H.I.M. Emperor 
William H. and by H.LM. the Eang of Wurtemberg, 
but also by national enthusiasnL He was advised by 
those admirable meteorological aeronauts who grace 
German science, and among whom figure Hergesell, 
Assmann, Berson, kc 

Conceiving an immense dirigible, he sought to secure 
indeformability or rigidity by construction : he designed 
a gigantic airship 130 metres in length by 1170 metres 
in diameter, and with a capacity of about 12,000 cubic 
metres. Its form was of a cylinder having coned ^ds, 
the elongation being equal to 11 (Fig. 37). 

Rigidity was secured by means of a metallic frame- 
work, in aluminium, which not only gave to the system 
the rigidity much sought after by its inventor, but he 
also divided the huge cigaf into numerous compartments : 
17 in all. Each of these is 8 metres long, except those 
5 and 13, which corresponded to the two cars, and which 
are not more than 4 metres in length. The rigidity of 
the skeleton is secured by transverse partitions formed 
of cross-bracing covered with fabric. It may be seen 
that this balloon is not provided with a ballonnet. 

Each compartment contains a balloon of india-rubber 
fabric partially inflated (nine-tenths only) ; the inflation 
of these 17 balloons is a lengthy and difficult operation. 

The whole of the skeleton is covered with stretched 
fabric. The two cars are attached to the balloon in a 
rigid manner, and connected by a bridge, along which 
slides a counterweight. The two motors are of 170 
horse-power, and drive four propellers of 1*30 metres 
diameter, running at 800 revolutions. 



Such a mass is difficult, if not impossihle, to handle 
upon the ground ; so its sheltering hangar is a floating 
shed, anchored upon Lake Constance. This *'dock,'' 
held only at one end hy a powerful hawser, swings itself 
round under the action of the wind, so that the entrance 
is always to "leeward" for the emergence of the 

Such is — or rather such was — ^the aeronautical leviathan. 
The Grerman military authorities, as a condition of its 
definite acceptance, demanded the accomplishment of a 
raid of twenty-four hours " without descent or revictual- 
ling." It was during the summer of 1908 that this 
balloon, the fourth built by its learned author, attempted 
this official trip. After several short flights, carrying 
successively the King of Wurtemburg, the Queen, and 
some royal princes, the Zeppelin set out on August 4, 
1908, from its hangar at Friederichshafen. There were 
twelve passengers on board. At 6.45 in the morning it 
rose above the lake and set a course to the East ; it 
passed over Basle, where it veered round to the north ; over 
Mulhouse and Strasburg, where the clanging of church 
bells and the salvoes of artillery heralded its passage; 
at 2.45 P.M. it was over Mannheim, when, before reach- 
ing Mayence, there was a slight "mishap." The fault 
repaired, the balloon resumed its journey, passing over 
Mayence during the night, and the return journey was 
commenced ; at 6.30 a.m. it was south of Stuttgart 
Some miles south of this town another accident neces- 
sitated descent. A squall struck the balloon, and from 
a cause still but little explained the immense airship was 
completely destroyed by fire in a few moments ! This 
was a national loss for Germany, and in a magnificent 


reak of patriotism a public subBcription raised in a 
days the millions of marks necessary to replace the 

Turned aboub 


6f r 

OEchterdSzKqm ^^Sfuffe|apd 

V destro/edlAaiS ^ ^^ 
A I 2. pjn 




SVSriX2LBR.l^>N.N D 


to. 88. Voyage of the Zeppelin^ August 4 and 5, 1908 (606 kilometres, 
endiug in the destruction of the airship) 

il vessel. Such is a beautiful example to be followed. 
ing the erection of the new airship Count Zeppelin 
^mmissioned Zeppelin No. III. 
at Zeppelin No. IV. accomplished a magnificent per- 
lance: its voyage of August 4 and 5, 1908, covered 


as a matter of fiekct 606 kilometresp with two descents, 
and an actually travelling stay in the air of twenty hours 
forty-five minutes. With the new Zqppelin the record 
for duration and distance was excelled on May 31, 1909— 
1 1 00 kilometres in thirty-eight hours ! Unfortunately the 
difficulty of handling such a mass as this again proved 
disastrous, for the airship came to grief against a tree. 
Despite its injury it was able to return to its hangar 
after completing this magnificent journey. 

Two other balloons, less bulky but more manageaUe, 
have been built by two German officers : MM. von Gtobb 
and von ParsevaL These airships are non-rigidL The 
first made a beautiful flight vnthout descent — ^thirteen 
hours. Afler having for a long time persisted in the 
adoption of airships of sausage form — i.e., cylindrical 
with hemispherical ends — the German aeronauts have 
decided to revert to the tapering ends indicated by 
Renard. The Gross has even adopted the stabilisators 
ot' the Lt'bauJi/ and the Patrie. 

In England military aerostation was represented by 
the construction of a vessel, the Xulli SecundtLS^ trials 
with which, at first satisfactory, had an xmfortunate 
termination. The career of this dirigible was short ; but 
no doubt we are only staying further progress to produce 
at one stroke somethiuij strikioiX. 

In Itiily Captiiiu Ricaldoni has constructed a remark- 
able dirigible alter the principles of Renard, which 
is one of the most pertect that has been realised up 
to the present- A Belgian sportsman, M. Goldschmidt, 
has built an airship beivring the name Belgique ; it has 
two separate motors of oO horse-power each, two screws, 
and capacity of '-700 meti-es : its length is 54-80 metres, 


naster-diameter 9' 75 metres ; it can lift four per- 
remain ten hours in the air, and travel at 40 kilo- 

Fio. 80. Toyage of Zeppelin IIL in a olofod circle (April 1909) 

iS per hour. Its radius of action is therefore 200 
etres. Stability is assured by a cruciform stabili- 

Stem ballonet 


nard ballontt 

Steering rocUen 

air pipe. 



FiCk 40. The Qerman dirigible Parstval 

This airship was constructed at the ateliers of 

reover, an aeronautical construction society has been 
ished in Belgium. Strongly supported, it has 


mider way a pcTPatlal aiiihi|i» Xa .Rbniirv, of 6^ 


We see many typw cxf dirigible belloonaj widely dif- 
ferent firom (me another. Each coti esp c Mi dB^ in short, to 
a new idea ; eadi, (me may eay, indicatee a develepnient 
But what ia the net reeolt? In aborts whidi is the 
beet airship? 

The problem is complex, more complaz even than in 
the (sase (xf vessels where there is something to go upon. 
I have accordingly attempted to resolve it, and I hope» 
even if it b not complete, at least to have introduced a 
new fiustor in aeronantics — the ** co-efficient of advcmtage'' 
of dirigible balloons. 

To discover a mathematical formula combining speed 
with the shape of the aerial vessel, mcytive power, and 
dimenaionB of the propeller, is still somewhat impossible^ 
there being many factors to take into consideration to 
formulate such a calculation. But, inspired with the 
example of Dupuy de Ldme in connection with steam- 
ships, I have sought to find an ''empirical'' fonnula. 
On the basis of results of experiments spread over a 
period of fifty years, the clever engineer evolved a 
formula called the '' French marine formula," which has 
the advantage of simplicity. 

By a slight modification I have applied it to aerial 
navigation. This is how : the power of the machine, 
expressed in horse-power, is taken, and divided by the 
number of square metres contained in the maximum sec- 
tion of the envelope. This gives a quotient, of which the 



cobe root La then extracted. The independent speeii i-i 
the airship, ezpreaaed in mTriametres per hour, is no^ 
divided by the above cube root : the result is a numc«. 
eshcays hettceen 3 cmd 5, which qualiiies the airship — diii 
is i&t coefficient of advofn^age. The value of this nnznb^ 
takes into conaideration all charactenBtiGs which theorr 
IB fttill powerless to calculate correctly — shape of lon^I- 
tndinal section, resistance to air, dBiciency of motor; as 
well as pitch, slip, and efficiency of propeQ^r, &c. 

Tn working with a number of dizigLbles of wUch I 
have been able to obtain d^nite data, I 
case been able to deduct an individual 
is ^ven in the following Table. 

Therefore, by means of such a method of " rlmiHii n 
tion/' ''rating" the balloons in their order of merit 
absolutely the same as if by trial, it is possible by means 
of the indication of form attached to each unit to com- 
pare one type with another. The more the co-efficient 
\p, in tho neighbourhood of 5 the more advant^igeous ]s 
tbo airship, whereas its efficiency is inferior if the 
r/r^^fficient drops below 4. 

Tfiin simple method shows the superiority of Colonel 
fV^nard s ideas. The form of all dirigibles which does 
not f/Jlow that of the fish, which he maintained to be 
in^IiMfif'JiMablo, have an inferior co-efficient- The Zep- 
jtrlin, notwithstanding its huge elongation, reaps but 
c^liaht fi/lvant'ige from its motor. On the other hand, 
Aa France, built twenty-five years ago, has an excellent 
r.ff ^!nir.i*!nt. The best are the Patrie, the lUpublique, 
urifl JJio Italian dirigible. Furthermore, the co-efficient 
i and G of our military balloons of the Repvhlique type 
m f&/]rlitionally remarkable, inasmuch as these balloons 

/■*>•f'^ Gffiiwintfi 



^e 60 horse-power motors, and always carry a 
Lount of disposable ballast — from 700 to 800 


pointed out that the co-efficients inferior to 4 
fusiform or cylindrical balloons, one may go 


of Dirigibles.1 


tion of 
length to 



Value of 




?.) . 






i-L6nu (F.) 






r (P.) '. . 






10$ (Renard et 

(P.) . . . 






wumt (F.) . 






[P.) . . . 






.) . . . 






bayard (P.) 






« (P.) . . 






[Oyl.) . . 






//. (P.) . 






lUdien (P.) 






nd say that in all pisciform balloons having the 
iiameter at the prow, the co-efficient of advan- 
always he between 4 and 5. 


lependent speed of 45 kilometres per hour may 

be considered fulfilled by airships commercially 

)&dL to-day. This speed enables them to set out 

F.): fusiform; (P.): pisciform; (Oyl.): cylindrical. 



in the vicinity of Paris with the certainty of being aUe 
to cope with the wind, and to steer in all directions for, 
on an average, about 300 days during the year. Sudi ib 
a remarkable achievement without a doubt, but it is not 

A speed of 70 kilometres per hour, that is 20 metres 
per second, must be attained to enable them to go out 
on the average 350 days during the year ; the impossible 
days would thus only number fifteen per annum, and 
these would be wildly tempestuous daya Will it be 
possible to attain these speeds, and to increase Uie 
velocity from 13 or 14 to 20 metres per second? Such 
will probably be reached, but it will be difficult, since it 
will be necessary to employ more powerful moton. 
Calculations show that if 13 metres per second are 
obtained upon a certain airship with 100 horse-power, 
it will be necessary to use about 450 horse-power to give 
the same vessel a velocity of 20 metres per second; 
undoubtedly the motive power must be divided be- 
tween two engines and two propellers. Thus a much 
more powerful motor, that is to say heavier, would have 
to be used, consuming four times as much fuel, and the 
aerial vessel's radius of action would be decreased. The 
balloon itself would have to be provided with a stronger 
and heavier envelope, to be able better to resist the greater 
thrusts that the increased speed would bring to bear 
upon its surface. Perhaps it would even be necessary 
to resort to compartments, which would increase the 
weight still more. 

The solution of high speed demands consequently that 
airships shall be far larger and carry far more powerful 
engines. But then another point arises, that of the 


resistance of the air, which is proportional to the square 
of the speed. Again, the balloon will assume an inclina- 
tion, and will lift its nose slightly, the action of the air 
will tend to lifl the envelope as it lifts a kite, and one 
consequently reflects whether, in the case of an airship of 
large dimensions, the naturally rising balloon, travel- 
ling at a certain speed, would not be able to sustain 
itself in the atmosphere without aerostatic interven- 
tion by the Archimedean thrust, solely by the effect of 
the velocity of the air upon its suitably inclined surface ; 
in other words, whether it would not be advantageous 
under these conditions to dispense with the " aerial 

Colonel Benard calculated that, with an airship of the 
dimensions of La France, this result would ensue when 
the speed attained 72 kilometres per hour. In that case 
there would be no more need for the encumbering, expen- 
sive, and dangerous hydrogen, and we would rise into 
the air under a purely mechanical effort by an apparatus 
heavier than the air. 

This brings us to the study of this second form of 
aerial navigation which has so brilliantly commenced in 
the form of the aeroplane. 






The *'hbatibr than air" problem: Birds and kites: The 


PORMs or AVIATION : The aeroplane 

Aviation is the art of lifting and propelling through the 
atmosphere a hody " heavier than the air," by utilising 
the resistance offered by the gaseous element to the move- 
ment of the bodies which are plunged therein. 

If the first successes of mankind in aerial navigation 
were due to the invention and use of aerostats, un- 
doubtedly his first ambition was to emulate the birds, 
which themselves are '^ heavier than the air." As a 
result it required centuries of intellectual struggle to 
conceive the physical principles upon which are based the 
action of the aerostat, whilst Nature placed under our 
eyes the birds, those marvellous travellers of the air. 
Consequently it may be affirmed that it was aviation 
which from the first haunted the minds of those ambitious 
to travel through the atmosphere. 

To-day the solution has been found, and although bear- 
ing in mind that mankind has not yet realised in a satis- 
&ctory manner the solution presented by the birds, yet 
the problem has been resolved by three quite distinct 
types of flying apparatus. These 


lit THE casf^cEsrr of the aik 

edled ortiiaplAraB), a^ft- 
_ _ to imitate the biids' method 
of I'l'^'^" **^ -"Ttrrtititrn : 

fMuatim vhidi doqityineB the metion«f 
mnchfeiHMtainingeefe moving aiMJetBeriiig 
in the air; aod finally, 

Aervplama^ ntiliBng hj hige dbliqne sarfiuxs the 
waiafauft <rf the air fiir their saatentatiaD nnder a hori- 
nontal qieed imparted hj a aereir-pnpeDer. 

Qmithoptirea hare onfy been raidy tried. Hdioopttraik 
Tecy faariniting at firat^ are now relegated to a aeooad 
pontaon. Only aeraplanea, the atnd^ of which haa ool^ 
been potaned really rationally during the paat two yeai% 
haTO dewekfped with aocfa rapidity, and^fbmiahed BOoh 
contrindng proob of th^ practioal Yaloe during the part 
twenty-fimr montha, aa to csnafale it to be affinned that 
they have at last aolved the problem of aviation. On- 
aequently we shall devote the following pages almost 
exclusively to their study. 


Before commencing to discuss aviation, such as it has 
been to-day fulfilled by man, it is indispensable to examine 
somewhat, aviation as practised by birds, those inimitable 
natural aviators, the Latin name of which {avis, bird) has 
moreover provided the appellation of the new trans- 
atmospherical locomotion. 

Being heavier than air, birds sustain themselves therein 
by utilising the resistance of this element to their move- 
ment, which resistance, as we have seen in speaking 
al)0ut '' dirigibles," is proportionate to the moving surface, 
and increases as the square of its speed. Birds oppose 


to the air verj large " sustainiDg " sur&ces, called wings ; 
they have an organ, the tail, for balancing and guiding, 
and the complex movements of their wings which, striking 
the air, secure therein a fulcrum which enables them to 
propel themselves forward. 

The flight of birds, which for a long time appeared 
mysterious, but as Marey's works completely elucidated, 
18 effected in three distinct forms. 

There is, first of all, the oary flight, wherein the birds 
flap their wings both to keep themselves up and to move 
about as desired. 

Then, there is the soaring flight, which the bird 
practises when, hurled on at a great speed, it ceases 
flapping its wings, only spreading them out, and, by virtue 
of their lai^ surface, gliding on the resisting molecides 
of the air, having only to steer while moving forward ; it is 
this phase of the bird's flight which the aeroplane imitates. 

Lastly, certain large birds, such as the albatross 
and the frigate-bird, practise the sail flight, in which, 
without muscular eflbrt, they depend upon the varying 
wind velocities, the " squalls " which occur in the atmo- 
sphere. When the bird feels the speed of the wind 
increasing, it faces the latter, and with winga outspread 
allows the wind to bear it along, both in ascension and 
progression. When it feels that the squall has reached 
its maximum speed, and is about to decrease, it turns 
ronnd and glides, owing to the velocity and altitude it 
has acquired with the wind behind ; during this gliding 
it can attain and maintain high velocities, therein bringing 
into practice the soaring plane ; when it feels a new squall 
coming, it turns round again, head to the wind, and the 
same cycle of operations is repeated. In this manner it 

lax itmie: (LummnEssr ow hme Jksm 

tiliiliaeft tliBrwihiii^QiQBLy WAciBticniftwilduiuLanY muHindar 
ddbrtsftotdiar tiimL tiiaaHiiBiBflHU!y Qsc mvesmigr fimiL bios 

^mftdn^ by tbsr tfiustuadiig: inacgiafitiaEfF of tba^ intouwtj 
of Afafr susseflB?^ar aqimlla^.'willeETOn. niBiiBgiS'lXi ^gyuLnpoK 
tther wimiL" 

mv&ce of die- ^nunf]^. iib mmp h» ac&niibtaefi \Sast t&qr 
(Mnginate: frmni tdift ^wying: cfftfiHrtatiiiff of t&fr huriaootel 
winii bjr tih& projisituiiiff pixiiiiiffiminiBfjr aeaistaacmi sfaost 
(gmatiinifang tiiifr tscceatciaL fHu?(iiigtt- ; buii it bos afteB. been 
pRfved t&jBUH mmk: aqnolb ^sk aii gp&uti aiamaBp&erir aid- 
taR&&. Wlkoitt,. t&ffiOi. is tditt (suiHfr^' WiooM tibffjr be dae 

iiifp aft to' w^isthiHr in0E& dir lisaiF dj^wpiB- dDoradi iciteiiapi 
t&e pimnagfr of' tsike- ami s iskjos^. ami t&ns ipwlace vneqail 
beflftnair ai t&e- atanoanftsciBal maaaes ? 

ITatuI <*air^iil Q&fi«rvuii!ibns^ aire moiiev b^* aaroatatic 
mesuia, conctanfiing nhm phtmomena, ^rdiSftl to aerial naTiga- 
tion^ one <!armot ban be satniedtid with, the fine conception 
6^ the (ij>Tia>mTi?aJ :§t&te ot* tihe ti^tmosphere^ set &xih faj t 
dever French engini*«Kr^ )L R*. Sor^an^ an old pupil of 
fthe Eo^le Potytecfi n Ti]^Tie-^ PwatienLt of the Frendi Aoial 
5fa^ijb^aion SiMTiety^ ihp.d a msui wiiose excdlent theo- 
retic^U itndies ha^re perhapi^ most coatriboted to the 
•'* anra-velling ^ o€ so complex, a qniesfeioii as- aTiation. 

M. Soreaa compajras zh/i centre oi tbe atmoephere 
with that of the firee smrtaice of the ocean, always 
tra^vwaed by ^* wave "^ systems obeying rhythmical well- 
4^tennined laws, and rhe "^ swell ^ of whidi is tiie most 
(ir>mtnonpIaee and simplest manlfestatioo. According to 
tim dever engineer, the atmosphere would he the seat 


of analogous aerial waves, communicatiDg to the gaseous 
masses, isochronous vibratory movements, the progress 
of which would be so much the more regular because 
they would be, at such an altitude, too distant from the 
ground and its projections for their regular propagation 
to be susceptible to confusion. It is from these 
''atmospherical waves" that the bird would profit in 
most cases of sailing flight. 

Will this sailing flight ever be accessible to man ? 
Taking into consideration the more and more powerful, 
and at the same time lighter and lighter, motors, which 
he constructs, will man ever be in a position to obtain 
its realisation ? For my part, I do not think so. But 
it is interesting to bear in mind this variety of flight, 
which we see practised by birds having a large spread, 
the '' great sailers " as they are called, which cut the air 
above the ocean, the fury of which is let loose by the 
tempest. Even then, they will utilise those '^ ascending 
currents of air, " caused by the reflection of the prevalent 
wind upon the oblique slopes of the immense waves of 
the Atlantic and of the Southern seas, where the height 
of these liquid hills reaches 16 to 18 metres : this would 
explain why, by resorting to this sailing flight, these 
** birds of the tempest " always keep quite close to the 
disturbed surface of the ocean. 

As to the " circular " flight practised by birds of prey, 
this is a soaring flight ; and sometimes when these birds 
are seen rising, gaining height whilst describing their 
majestic rings — as does, for instance, the buzzard — it is 
because in so doing they utilise an ascending current of 
air, which is often produced in summer above ground 
particularly heated. 


Thus, when soaring, the bird moves without effort 
But a deep study of its movements shows that its wingB 
fulfil two distinct functions : propelling and sustaining 
surfaces respectively ; and it is especially the extremities 
of the wings which propel the animal, the middle part 
serving principally for sustentation. 

Why has man not sought for the solution of the 
problem of aviation merely by the imitation of the flight 
of birds ? It is because human thought has conceived, 
has realised, a more general and more efficacious me- 
chanical movement than those which exist in Nature; 
this is rotary motion^ of which Natui-e does not offer 
us any example, except in regard to celestial bodies. 
But there is a reason for this ; it is because all living 
beings being liable to growth as time progresses, their 
propelling organs must lengthen freely, in proportion to 
this growth ; this would not always be possible in com- 
bination with rotary organs. 

Man has therefore sought — and success has shown 
that he did so with reason — to accomplish high travelling 
speeds on land and sea by means of revolving apparatus : 
wheels, screws, turbines, &c. ; he has thus been able to 
attain and to exceed the speed of the fleetest of animals. 
Now, why should not what is good on land and sea also 
suflSce for the air ? We do not construct motor-cars with 
jointed feet nor transatlantic boats with fish fins. We can 
therefore seek for propulsion in the atmosphere otherwise 
than by flapping of wings, and if we use these tuings 
for sustentation we must at least direct ourselves to 
machines and revolving propellers to move in the Aerial 



Pressure oflheair 

of Ac wind 



The excessive weight of the " human motor," a weight 
which approximates as we have seen (page 8) ahout 
1000 kilogrammes per horse-power, appears to forbid 
man the realisation 
of flight, by the use of 
his muscular power; 
the failure of all those 
who have tried to 
solve the problem of 
aviation in this man- 
ner may therefore be 
easily explained. ^®- *2- BquiUbrium of the kite 

But from time immemorial man haa found a means of 
raising in. the air bodies ''heavier than air/' and the 
" kite," this toy which in the course of a few years has 
become one of the most valuable instruments of scientific 
investigation, has been known in China and Japan from 
the most remote times. 

It is scarcely necessary to define the kite, which we 
have all handled, more or less; it is a rigid frame of 
wood and strings, on which is stretched a surface of 
cloth or paper; a string holds the apparatus to the 
ground, and when the wind reaches a sufficient speed, 
the contrivance lifls itself into the air ; if the surface of* 
the kite is large enough, it may even lift objects — 
meteorological instruments or photographic apparatus. 

The equilibrium of the kite is easily explained by the 
combination of the forces which bear upon it (Fig. 42). 
The surface exposed to the wind is, in fact, kept 
"oblique" in relation to the direction of the latter. 

: I ^*«_«>i:*.iti <^ ai. jmti\. 

Tig^ ^infi lMiijW if 



€if ffe kiteft difidoB 

dketllj tiha tfciwit of the 
€E dbeciner ■uppoBod to tintof 
anmjs oBrtrayod. l^ the 
taJBM to he wlBrirMllj wmmtnA^ ani 
Dot to biedc andcr Ifce dEiit to windh it i» Bulj o c fa^ 

Under tbew eondhiaoB^ the eonfarrranoe ii in eqm- 
UbrinnL Let one of the abore fixeeB be TBried, and 
c^aOibriiim wOl be disturbed immediatelj. If it is the 
wind that increaaeB, its iM ea sme beoomea atronger, the 
vertical force increases, and the kite riaea. !£, on the 
contrary, the wind did not change, and the weight of 
' the apparatus shoold unexpectedly be augmented as, for 
infftance, if it should rain, the kite fiill& Lastly, if the 
third force is annulled, that is, if the cord breaks, the 
kite is borne away by '' the wind." 

Buch is a veiy simple case of an apparatus, which lifts 
itneU by utilising two forces : (l) the resistance of the 
air ; (2) the tension of a cord, which may maintain the 
surface exposed to the wind. There must, of course, be 
a wind to lift the contrivance. Now there are some 


days when there is no wind. What is to be done then ? 
Children, the traditional operators of the kite, do not 
allow such a small trifle to stand in their way. There 
is no wind ? Well, ** they make some," by running as 
quickly as their legs will carry them, for it must not be 
foi^otten that wind is not an absolute thing ! It is the 
relative movement of the air in comparison with a body, 
and this movement may take place, either if the air 
is in motion and the body motionless, or if the air is 
still and the body moves rapidly in it. It is for this 
reason that in a motor car one has a sensation of '* wind" 
even when there is none. And children, by following 
these instinctive actions, in one stroke invented and 
realised the aeroplane. 


An aeroplane, in fact, is nothing but a kite which 

'' creates its own wind," to accomplish which, the string 

is replaced by a motor, and a screw which gives it 

a speed equal to what the wind would have to be to 

support it like a kite, were it retained by a cord. 

The tension of the cord is replaced by the power of 

propulsion (Fig. 43), and the conditions of equilibrium 

are, at least fundamentally, quite as simple as those of 

the kite. An aeroplane will therefore be composed of a 

supporting surface divided into one or two parts, which 

are often called the wings^ cutting the air in an oblique 

manner by means of a propeller and motor ; it will be 

connected to a shff or car^ in which ynil be the aviator, 

the motor, and the mechanism for steering, comprising 

at least two '* rudders " ; one a '' steering rudder," to go 


ti^xt (St [fftf; auui tsfie 


Fk. til Eiivlihriiim. of siia 

it, the 
e&et of wiiidi kaper- 
penifiRnlar/>reKfFg upon 
thexDormfaleplmiieL Thk 
preBBore mj be lepboed 
by two other IbcoeB ; ooe 
Tcrticftl^ wfaiidi t^ids to 
lifk the eontiivmiioe, bj 
annollmg the efBsct of its 
iTfi^A/, which would XeoA to mmke it fidl ; the other, 
horizontal, directed towards the stem, and tAnditig to 
retard the speed of the i^jparatua Therefore equili- 
brium is realised when the speed due to the motive 
power is sufficient for the thrust to be able to lift the 
weight of the apparatus. This speed is thus called the 
'' critical speed/' and the aerial vehicle will continue its 
travel in a straight line so long as the forces which act 
upon it retain their relative values. 

But if any one of the considered forces should change, 
the equilibrium will be immediately destroyed. For 
instance, if the speed of propulsion increases, the pressure 
also increases, and therefore also the resultant vertical 
lifting component. The weight not changing the equi- 
librium is destroyed and the apparatus will rise; it will, 
on the contrary, descend if the speed of propulsion 
decreases ; it will also descend should the ^' supporting 


sui&oe" for some reasoD or other be dixnimshed, in the 
same manner as it will rise, if the weight of the apparatus 
becomes less, which oocotb during a jonmey, on aocx>mit 
of the oonsomption of the fael feeding the motor. 

The very simple conditions of eqnilibrimn which we 
have examined are, therefore, precarious, and the problem 
must be investigated a little more dosdy to seek the con- 
answering the requirements of cnirent practice. 


To learn exactly what will happen when the regu- 
lating speed becomes varied, we must hearken back for 
a moment to the laws of the resistance of the air, which 
are fondamental in the matter of aviation. 

Let us consider (Fig. 44) a movable sorfstce, inclined 
in the direction of its advancing movement. The re- 
sistance of the air increases proportionately to the 
spread of this surface, in proportion with the square of 
the speed at which it is driven, and increases at the 
same time as the angle at which it is inclined to its 
trajectory, and which is called the angle of attack. 
Consequently, if this angle is very small, the resistance 
will be very slight ; but on the other hand, the lifting 
effort will be a more considerable proportion of the 
thrust (Pig. 45, No. 1), whereas the resistance to advance 
will be a fraction less. If the angle of attack increcises 
(Fig. 45, No. 2), immediately the thrust becomes stronger, 
but the proportion of this thrust, which constitutes the 
lifting power, decreases if more inclined on the vertical, 
whilst increasing that opposed to advance. 

It will, therefore, be * necessary to seek the optima 

Ifovmd surface. 




value of the angle of attack. Calculation and experi- 
ence agree that It must always be very smalL 

But a more unin- 
terrupted study of 
the resistance of the 
air upon a surfiu» 
inclined in motion, 
shows us something 

Fio. 44. BeeiBtanoe of the air upon a sUnting OVen more important 

•'^'^^■^ We have supposed, 

in the elementary explanation which we have given d 
the conditions of equilibrium of an aeroplane, that this 
was absolutely symmetrical, and that all the forces whidi 

cf wind. 

Lifting power. 




-M— -. 


Dix^ction of inavement. 


Fio. 45. Influence of the angle of attack 

act upon it were applied to a common point G, wbidi 
would be its centre of gravity. In practice, things do 
not happen so simply. 

In reality the point of the moving surface where the 
pressure is applied, a point which is called the " centre 
of thrust," does not coincide with the centre of gravity ; 
it is the nearer to the front edge of the moving surface, 
as the angle of attack is weaker. This is what experi- 
ment demonstrates : if one moves forward perpendicularly 
through the air a flat surface, which squarely cuts the 


moleculee (fig. 46), the phenomena are Bjmmetrical, uul 

tiie thrust will be exercised at the centre of gravity itself; 

bat if the moving 

plane is inclined 

(Fig. 47), the gaseous 

molecules hare much 

more difficulty to 

xise up under the 

entting edge than to 

go downwards to gain 

the other side. The 

thrust will therefore 

be greater on the 

front extremity up 

which they are forced to travel, and the centre of thrust 

will he nearer the front edge. 

This position away from the centre of thrust alters 'r 

Fio. 46. Tkt Burfaca kdTuiaiDg nonuallj throoch 
tbe sir. The air ihoImdIm gliding ijinnietri- 
Mllf around tha enda 

FlO. iT. The Burtaoa adruidDg obliquely ttirongh the air. The gaseoua 
nwleculei gliding past in a diwjniinetrical maDaer 

the conditions of equilibrium of the aeroplane, and 
affi>rds us some data concerning construction. 

Let us consider an aeroplane (Fig. 48) progressing 
with a very small angle of attack. The centre of thrust 

LiFtrinJ force 

of movement 



will, as we have just seen, be brought forward to a point 
near the firont edge. The lifting effort applied to this 
centre will therefore no longer be directly oiq>osed to 
the weight, the latter b^g always applied to the 
centre of gravity. The disposition of the two forces will 
therefore tend to cause the sm&ce Qf the aeroplane to 

turn in the direction 
indicated by the 
curved arrows shown 
in the figure. 

Moreover it is 
necessary to observe 
that the position of 
the centre of thrust 
is not fixed, it varioi 
for each value of the 
inclination of the aeroplane, and advances more 
towards the firont as the angle of attack is made 
sharper. This is not all ; let us suppose that, through 
an accident or even an incident on the way, the moving 
surface should incline towards the bottom ; the air 
would then strike from above, and this would mean 
a certain rapid and fatal fall. A means must therefore 
be found for readjusting the aeroplane when it inclines m 
the direction of its length ; this means is the '' feather- 
ing " or empennage. 

The empennage will comprise a surface placed well to 
the rear of the sustaining surface (Fig. 49) to which it 
will be joined by a "connection" which, being light, 
rigid and latticed, offers only a minimum of resistance 
to the air. Under these conditions, under the influence 
of the thrust applied forward of the centre of gravity, 

Fzo.i8. JSqnUibrinm of the Mtiial MropUune 


where the weight acts, the aeroplane would tend to turn 
as shown in Fig. 48, in such a manner that it would have 
its stem lowered towards the ground ; but the thrust 
which is exercised upon the empennage, a thrust acting 
with the aid of the long 


Movement for 


of gravity 

Centre of 




" lever arm " repre- 
sented by the rigid 
connection, lifts and 
brings the apparatus 
back to its lawful in- 
cline, in accordance 
with the calculation 
concerning its dimen- 
sions and motive power. 

In the same manner a "fringe" (Fig. 50) not very 
high projecting towards the stem of the sustaining 
surface would become " effaced " behind the front during 
the journey with a normal incline ; but if the apparatus 
were to become inclined towards the bow, the air strik- 
ing this fringe which 

Fio. 49< Aotion of the empennage 


Directipn of iTLOvcmcnl 

Fio. 60. Aotion of a Yertical "fringe" at the stern 

would find itself un- 
masked by the acci- 
dental lowering of 
the bow, would act 
upon it, and this 
action, bearing on 
the stem, would lower it, and would restore the aeroplane 
to its normal incline. It may therefore be seen from 
these two examples that it is possible to give an aviation 
apparatus an automatic longitudinal stability. 

Let us remark that kites for a long time past have 
been fitted with this very simple means of longitudiual 


stabilisation ; they are, in &ct, provided with a tail. 
This does not only serve as a counterweight to the 
stem ; a piece of lead at the bottom of the framework 
would answer this purpose without ensuring stability. 
The tail acts as a true stabilisator, and kites mtist be 
provided with it ; we shall, however, return to this 
subject in the course of the next chapter. There is one 
other question, also vital for balancing the aeroplane; 
it is transversal stability. But in this question, the 
shape of the wings, dimensions, even the construction of 
the apparatus, are inferred as being known. Therefore 
we will here conclude this explanation of the general 
principles, to see, now, how they are applied to the 
conception of a projected flying machine. 




From theory to practice: The wings: Monoplane or bi- 
PLANE : Stability, and the means for realising it 


Wb have seen, by what effects of the resistance of the air, 
a flykig machine may be sustained in the atmosphere. 
We must now see in what manner we can most advan- 
tageously utilise these effects. 

First of all, must flat or concave wings be used ? This 
is the first question one asks. If we take as example the 
wings of birds, which are their sustaining surfaces for 
soaring, we notice that they are always concave under- 
neath. Since the first attempts at aviation, constructors, 
therefore, have always sought to build wings distinctly 
concave, the concavity being turned towards the earth. 
Experience has shown, moreover, that a slightly concave 
snr&ce towards the bottom gives to the aeroplane, for the 
same speed, a lifting power much superior to that obtain- 
able where the flat surface was carried right to the ex- 
tremities. Further, M. R. Soreau, in a very fine calcu- 
lation, has shown that for any concave wing a flat surface 
may also be determined, which would act as if it were 
connected with the concave surface in a rigid manner, 



and the bearing power c£ which would be the same as 
that of the concave surface, but that, at the same 
time, the concavity 

Air currm 

DsrecHonoMrKyve ment 

FXO. 61. A kMig And narrow mafmoB 

a "counter-resistance'' 
to advance, in other 
words, a force of re- 
action which sligbtlj 
increases the propelling 
force by acting in the 
same way. 

Calculation and ex- 

perience being, therefore, in agreement in the recom- 
mendation of concave surfaces, these are what we shall 
employ in the construction of aeroplanes. 

Moreover, the wings will be elongated and disposed 
at right angles to the length of the flying body. 

For this purpose imagine a wing, a rectangular shape^ 
measuring 2 metres by 4 metres, viz., 
8 square metres (Fig. 51). If we 
cause this surface to move in the 
direction of its length, the currents of 
confined air struck by its firont edge, 
after having barely crept beneath the 
wing, will escape lunder the edges 
to which they are in close proximity, 
and will no longer contribute to sus- 
tentation. If, on the contrary, this 
same wing be moved on its broader 
edge (Fig. 52) the currents of air cannot escape side- 
ways, because they are pressed back by their neigh- 
bours, with the exception of those which are at the 
extreme edges. In this second arrangement, all the 
currents thus contribute to sustentation. Our wings, 

Air currents 

[ II 1 III 



^ ^^ 

Direction cf travel. 

Fio. 52. A short and wide 


which we have aheady been induced to make slightly 
concave, will therefore be disposed transversely. 

This transversal arrangement of the supporting surfaces, 
moreover, is what we find with all the birds and flying 
insects; in birds par- 

Fia. 53. Bpreod of ft bird'i wing 

ticularly the 

of the wings is always 

considerable. (Fig. 53.) 

Besides, no matter 
what may be the extent 
of this spread, the sup- 
porting surfaces can be disposed in a horizontal manner, 
or form between them an angle more or less open, in the 
form of a very obtuse upright or overturned V ; this 
disposition of the wings in a V has been adopted notably 
by Captain Ferber for his aeroplane, whereas the wings 
of the Wright aeroplane are straight. 


Now arises a very important point, which Colonel 
Renard introduced into the study of aviation, viz., the 
principle of "sustaining capacity." 

Let us remark, first of all, that in any attempt at avi- 
ation there are two very distinct things. There is, first 
of all, the " Bustentation " of the apparatus in the air, 
and then propid^on in a given direction. Now propul- 
sion only requires very slight motive power, on account 
of the feeble density of the resisting centre ; the prin- 
cipal effort to be made is that which must be expended 
for sustaining the apparatus in the air, or, in other 
words, to realise a power of lilting equal or superior to 


Let us imagine an orthogonal aviator system, that is 
to say, one in which the lifting effort is achieved by 
surfitces vertically striking the air from top to bottom 
(like pistons in vertical cylinders, for instance) ; let us 
suppose that this contrivance weighs 100 kilogrammes, 
and has a total sustaining surface of 50 square metres; 
its load per square metre will be 2 kilogrammes. The 
work of sustentation^ under these conditions, would be 
equal to what would be necessary to lift the apparatus 
with a speed, according to experiment of 4*90 metres 
per second. 

Let us now suppose another aviation apparatus, con- 
ceived upon different ideas, and not belonging to the 
** orthogonal system," about which we have just spoken, 
but which, like it, had a total weight of 100 kilogrammes. 
The orthogonal apparatus, with its 50 square metres of 
surface, to sustain itself requires a work equal to that 
which would have to be expended for liftJng its weight 
of 50 kilogrammes at a speed of 4*90 metres per second 
If the new system, to sustain itself, requires a surface 
greater than that of the first — for instance, 75 square 
metres instead of 50 — we say that its sustaining capa- 
city is 0*66 ; it is therefore weaker. If, on the contrary, 
40 square metres are sufficient, always under the same 
weight and work, to realise its sustentation, we shall 
hold its principle of construction as superior, and say 
that its sustaining capacity is 1*25. 

The aeroplane, attacking the air slantingly, is a 
manner as simple as it is elegant for improving the 
capacity for keeping up ; in the same manner, the lateral 
disposition of the supporting surfaces, their concave form 
towards the bottom, particularly improve this capacity. 



We are led, by virtue of what has been said, to take 
light sustaining surfaces of a great superficies if we wish 
to raise a perceptible weight, as, for instance, a motor, 
propeller and aviator. Let us suppose that the calcula- 
tion based upon the data of experiments shows us the 
necessity of a bearing surface of 50 square metres. Will 
this surface have to be employed in the form of a single 
transversal wing, or of two wings, or even three super- 
imposed? Under these conditions the transversal 
''spread" is decreased, which, as regards the encim)- 
brance of the apparatus and its working efficiency, may 
constitute an advantage ; in other words, will the aero- 
plane be a '' monoplane " or '' multiplane " ? 

Birds are obviously monoplane, and they are, more- 
over, excellent monoplanes. Everything would therefore 
tend to design our aeroplanes as monoplanes were there 
not kites to recommend multiplanes, or at least biplanes ; 
and the indications of this popular toy must not be 
neglected, for, as Captain Ferber has so truly said, " the 
kite IB an anchored aeroplane." In fact, if the old kite 
is a monoplane, the '^ tail " constituting the stabilisating 
empennage, the modem kite is always at least a biplane, 
and the following will show by what series of trials one 
has been led to adopt this disposition, which experience 
has shown to be very advantageous. 

Let us consider a kite (Fig. 54 A) which we are flying 
in a very steady wind. So long as we do not seek too 
great a height, the apparatus will behave beautifully. 
But if we wish it to go higher and higher it must not 
be forgotten that as we imroll the cord it has to bear a 


praportiaD of the ahrays increamng weight. There will, 
dioHfare, be a height limit mbore vhich the weight of 
tlie onroQed eoid will exceed the carryiDg sur&ce, re- 
SDhmg from the Uirnst of the aii upon the cloth of the 
kite, and the latter would &1L An arrangement, as 

ne. 5A. Brolntioa ot tlt« oaUolar, from the InIlItiple^ kite 

simple as it is old, can then be employed, confiisting of 
an auxiliary kite attached at an intermediate point of 
the main kite cord, which will thus support a proportictn 
of the cord's weight. Such a contrivance will be able 
to rise to a much greater height thau a single kite. Tbe 
two kites may be placed a short distance apart, or be 
brought very close to, and parallel with, one another 
(Fig. 54 B), or they may be so made up as to form 
prisms covered with* cloth ; it is upon these lines, indi- 
cated by the Australian Hargreaves, that the modern 
kites of children (Fig. 54 C) are built, and those, larger 
and better constructed, which are used by meteorolo- 
gista for carrying registering instruments into the upper 
atmosphere . 

The " cellular " kite of Fig. 54 C is nothing else but a 


biplane aeroplane, provided with a *' feathering tail/' 
which secures its stability. 

We can therefore distribute our supporting sur- 
face upon two superimposed parallel planes; such is 
the design of the Farman, Delagrange and Wright 
aeroplanes, whereas those of Bl^riot, Esnault-Pelterie, 
Grastambide, Santos-Dumont, and the ''Antoinette " are 

Naturally we can make triplanes or quadriplanes, but 
one must not proceed too &r in this direction, as there 
would result a " pile of planes," the stability of which 
would be precarious. Here, as in all things, the happy 
medium must be found. An inherent objection to mul- 
tiplane construction must, however, be pointed out; 
the rigid supports which connect the planes together 
present a large surface of resistance to the air, and for 
this reason monoplanes are much their superior. 


We have obtained the longitudinal stability of the 
aeroplane by the use of the ^^ feathering tail." But 
lateral stability must also be secured ; in other words, 
the wings of the apparatus must not incline from right 
to left, or vice versdy during travel ; at any rate, if such 
an incline were perchance to occur, the apparatus must 
be constructed in such a way that it rights itself by its 
own effort. 

Now an aeroplane must be considered in two phases 
of movement ; that in a straight line and that in a 
curved line, otherwise called " turning." 

In the case of the straight line movement, the lateral 
stability is, if not ensured, at least very adequately 


fulfilled by the spread of the supportmg sor&ceB, 
the stretch of which counteracts sudden indinatioD. 
Moreover, the centre of gravity of the oontrivaiioe is 
always below the supporting planes (or the smftoe 
which would be equivalent to them) on acooont of the 
weight of the motor and passenger, a weight which 
would tend to right the apparatus if it were to incline 

But this is no longer the case when, describing a 
curved line, the aeroplane is turning. Then there inter- 
venes a complex phenomenon which causes it to indme 
'* within " the turn, that is to say towards the centre of 
the circle which the machine describes. This phencnneium 
is the unequal resistance of the air upon the two ex- 
tremities of the supporting wings. 

Let us consider an aeroplane (Fig. 55) turning about 
a centre, and let us suppose, to obtain a proper idea 
thereof, that the spread of this aeroplane is 10 metres; 
the circle which the centre of the machine itself describes 
will have, consequently, a radius of 15 metres. It is 
seen that, under these conditions, the extremity A of 
the wing turned towards the centre will describe durmg 
a certain time the arc of the circle AA', in passing from 
position (1) to position (2), whilst the outer extremity B 
of the same wing will describe, during the same timey the 
jirc of the circle BB', double the length of AA'. The 
exterior extremity B must, therefore, travel twice as fiif 
during the turn as the interior extremity, that is to say, 
in one word, go at twice the speed of that of the inner 
edge, A ; and as the resistance of the air is proportionate 
to the square of the speed, the result is that the interior 
extremity A, moving less quickly, will be subjected to a 






lesser resistance from the air, and therefore will be less 
" sustained " by the air than extremity B. Therefore, 
during the turUy the aeroplane m/ust incline itself more 
and more towards the centre of the circle which it 
describes^ as the radius of the turn is decreased. 

We can confirm this by figures, and in a very simple 
manner. If the speed 

of the outer wing is 
20 metres per second, 
that of the inner 
wing, in the example 
we have selected, will 
be only 10 metres. 
The lifting efforts will 
therefore be no longer 
equal, but will be 
between them in the 
proportion of the 
square of 20 with the 
square of 10, that is 
in a proportion of 

Bl .*.-—*.. 

••..^i^Axis on which 
/;i\x it tOrns 

/ 2!\ V 


Fia. 65. An aeroplane turning 

400 to 100. It is, therefore, seen to what degree the 
equilibrium will be destroyed. It is true that an aero- 
plane will never have to make so '* short " a turn, and 
we have purposely selected an extreme example; but 
such always exists, and lateral incline must absolutely be 
guarded against while turning. 

This natural incline, however, has its advantage; it 
appreciably counterbalances centrifugal force^ which is 
unavoidable in any curvilinear movement, and is the 
more important in the aeroplane inasmuch as the surface 
of lateral resistance of the latter is weaker. Major P. 


Renard even proved that inclination of the aeroplane 
was essential to combat the centrifugal effect. This 
inclination lowers the trajectory. Therefore, aviators 
must rise a little before making a ** turn/' if after doing 
so they desire to retain their previous altitude. 


At all events, it is indispensable to keep up the hori- 
zontal supporting surface as much as possible through- 
out the trajectory, whether it be rectilinear or curvilinear. 
Several means may be utilised for this purpose. 

First of all there is a very simple one, which I am 
surprised at not having seen experimentally used, or at 
least tried, as it seems very rational to me. Since the 
** lateral inclination " is a result of the unequal resistance 
on the two extremities, let us equalise these resistanceB; 
we cannot prevent speeds from being unequal during 
turning, but we can cause the supporting surfaces to 
vary in the opposite direction ; we can increase the 
surface at the "inner point" A (Fig. 55) and decrease 
it at the outer point B. For this purpose it would 
suffice to carry at the extremity of the wings, varying 
surfaces, either arranged in the form of a fan and able to 
fold up in the same manner as birds' feathers, or of 
sliding ribs, one drawing back under the sails and the 
other extending by as much again. The surface of the 
inner wing which dips would thus be increased, while 
simultaneously that of the outer wing which rises would 
be decreased, and it would reduce the difference of the 
thrusts, that is to say, the cause of the inclination. 
These two movements could be produced automati- 


sally by a simiiltaiieoiis movement of the steering 

The celebrated Ammcan aviators, Wilbur and Orville 
Wright, have adopted anoth^* arrangement, "" warping 
Df the wings." The following shows in a few words how 
this is done. 

The extreme angles of their aeroplane can be moved 

Actkm of ihe Air 
tendinO lb depress 
tke left comer 
wkick ttumih^ 

Actum. oF air 

tending to J "^^ I ^^^^ Without \ 

liiFfc vdhuh S ^^r I "^^^^T^^d ^^ \ 

burning I y^ ▼ I aeroplane I 

lowers. ^ ^ I ^ttia J 

decline . ^ 

Fio. 66. Principle of warping the planes (Wilbor and Orrille Wright) 

ap or down (Fig. 56) absolutely like the " comer " of a 
visiting card. As the Wright aeroplane is a '^ biplane/' 
wooden battens lift up the corners disposed one above 
the other at the same time, so that when a comer 
of the upper wing is lowered the comer of the lower 
wing placed below the first is also depressed. The 
whole is governed by a manoeuvring lever pushed or 
pulled by the aviator, and when the corners on the left 
are forced down those on the right ascend, and vice versa. 
Under these conditions, it is easy to see how this 
arrangement permits of lateral inclination being dispensed 
with. A turn is taken, and the aeroplane has a tendency 


to incline inwards ; but the aviator immediately manosuT- 
ring his lever, lowers the comers on the inside of tiie 
turn and elevates those on the outer edge. And then, 
as is shown in the diagram, the effect of the air on the 
corners thus offered to its action rights the apparatus. 

M. L. Bl^riot, the French aviator, evolved and 
adopted on his aeroplanes some time ago, long before 
the arrangements of the Wright Brothers had become 
known, a very reliable system, quite as ingenioua, 
which does not require the wings to be deformed by 
warping : there is at each extremity of the fixed wings 
of his aeroplane, small subsidiary moving wings (Ailerons) 
(Fig. 57) capable of being inclined in relation to the 
sur&ce by turning about a horizontal axis. When 
turning the small wing on the inside is lowered in the 
interior and that on the outer wing is raised ; the eSed 
is the same as by warping the wings, but this arrange- 
ment has the advantage of not bringing about any elastic 
deformation of the frame ; this deformation, unavoidable 
in warping, must inevitably end in endangering the indis- 
pensable solidity. 

These various arrangements for righting are governed 
by the aviator ; it is therefore necessary for him to secure 
the readjustment of the apparatus himself to perform a 
special movement, completing that which he makes in 
steering to right or left when manoeuvring the flier 
by the rudder. But an automatic stabilisation indepen- 
dent of the will of the conductor, and fulfilled by the 
construction of the aeroplane itself has been sought for ; 
it is this solution which has been simply obtained by the 
Voisin Brothers, the French constructors who built the 
aeroplanes celebrated by the exploits of the aviators 


Farman and Delegrange. The arrangement employed 
hy them is ** partitioning " (Fig. 58) and applies to 
multiplane aeroplanes. It comprises the introduction 
of ri^d vertical partitions between the two parallel 
bearing surfaces. These partitions, owing to the resist- 
ance they offer to the air, oppose any deviation due to 
ce'liitrifugal force, 
and the surfaces 
combining with the 
sapporting wings, 
add resisting effort 
tocombat the lateral 
molination which 
thereby becomes 
pfactically elimin- 
ated. The aviator, owing to this principle of construc- 
tion has no longer to trouble about his equilibrium, he has 

only to think of steer- 

Fio. 67. The correctiDg aileronii (B16riot) 

ing. Let us remark, 
casually, that although 
it is true that the 
auxiliary surfaces of 
the partitions add a 
little weight to the 
apparatus, they do not 
increase, at least to 
any significant degree, 
its resistance to ad- 
vance as they cut the air with their edges and are set in 
the direction of travel. 

Lastly, there is the "artificial" stabilisation obtained 
fay the stabilisating organs bringing^ forces other than 


Fte. 58. Partitioning (MM. Voisin) 


•f l3kB air iito acas^ TMm ^fft of 

wHii • hesfj eiicuBifeM ce^ hsie tiiB nvtj inpartaBt 
MadiMikaJ qoaKfrf of only bainif fiiwrf to dsviita fion 
ilit noffml, the plane in whSA ratetion in dfartedJ^ty 
grant diffienlty and nfc tim ptiee ot n tqij grant «ftri 
The estent of tfaektter to facing abovt tins doviitioB 
h met mtM ffrantv an tlio tii r i rff i'g nnwa ia inBraaaod. tad 
ita qieed aogmpnted. li, thenfiMmp n gymafsagi^ is 
m oan t ad on an aerofdane and ita rapid rataiy moFoaeBt 
maintained by the motor, an eflbct is nucimnaiy to dayige 
tbe rotating phne eonaoiidated with tbe fiame of tbe 
amal Tehkle, and one may thna hopo^ in an nntomatic 
manner, to obtain lateral stability. Theoretically thk 
idea is excellent. In practice it is another thing. 

Firat of ally a gyroscope when constructed on a large 
scale is a very dangerous apparatus ; let it escape firom 
one of the sockets between which the extremities of its 
axis revolves and it then becomes a destructive projectile 
both of men and everything else ; serious accidents have 
already happened from this cause. In the second place, 
for it to be efficient, it must be fairly weighty, and 
in the matter of aviation, any extra weight is a very 
vital condition. 

Then — and here is the greatest theoretical objection 
which may be urged against it — it might, if it worked 
efficiently, compromise the solidity of the light frame- 
work constituting tbe aeroplana In fact, what causes 


the aeroplane to become inclined, is the effort resulting 
from the action of air resistance bearing upon all parts 
of its long sor&ce, whereas the gyroscope only acts at 
one single pcnnt of its firamework. It is, therefore, in 
supposing this means of stabilisation to be efficient, as if 
the aeroplane were pinched in a vice at one of its points 
and an inclining effort exercised upon the rest of its 
mechanism ; what would happen then ? Twisting would 
occur which might jeopardise the solidity of construc- 
tion. For this reason, it seems to me that the gyroscope 
would be dangerous if it really acted ; and if it does not 
act, it is a dead weight which it is useless to lug about 
in the air. Moreover, all this is only theory ; experi- 
ments alone, many times repeated, will be able to supply 
us with really reliable data. 

Let us add, that in order to increase the stabilisation 
the use of a double rudder at the bow and stern, moving 
in opposite directions at the two extremities of the aero- 
plane, has been suggested. Experiments have not as 
yet been sufficient to decide as to the practical value of 
this arrangement. Another means of automatic stabili- 
sation is that which was evolved and tried a short while 
ago, comprising the automatic variation of the '* angle of 
attack" by articulating the whole of the supporting 
wing around a horizontal axis. This wing is held in its 
normal position by a powerful spiral spring which resists 
the pressure of the air when the aeroplane is travelling 
at the required speed, but which gives way to this 
thrust, if the speed happens to increase suddenly, by 
diminishing the angle of attack. Experience will shov^ 
what this ingenious conception is worth. In any case, 
the ^'natural" means of stabilisation are the most 


rational, because they act with effiaoto analogous to those 
of the pertorbing fbroee of equilibrium. 


As we ha^e spoken of turning, the means by which 
it is brought about must be indicated. This is the 
** steering rudder." 

The steering rudder is similar to that used on boats 
and dirigible balloons ; it is a light and leeiflting thin 
panel, turning about a vertical axis, operated bjr a 
*' wheel '' or motor levers, at the will of the aviator, who 
can turn it either to the right or left. The rudder is 
placed as &r as possible to the stem of the aeroplaoe, 
and as &r as possible away firom the supporting surfroes 
(Fig. 59). When it is turned to the right or to the left, 
the moleculn of air, striking its surface in an bUiqiie 
manner, exercise a thrust which is all the mam efficient 
in causing the body of the aeroplane to swerve, since it 
is placed at the end of a long lever. For this reason, it 
is most frequently placed at the rear end of the empen- 
nage tail. When it is desired to travel in a straight 
line, the steering rudder is brought back to the central 
position, that is to say in the longitudinal plane of 
the apparatus, and the air no longer acting upon its 
surface, no deviating action as regards direction 

Let us remark that the steering rudder could only be 
efficient if the aeroplane present a '* lateral resistance to 
drift" An aeroplane which had no opposing surface to 
a lateral movement, would not comply with the move- 
ment of the steering rudder. There must therefore be 
a lateral surface, if only effected by the '* hull " of the 

l^'l fHB^^H 

* 7 / N 

/ / 

\ \« iP^^Bl 

^\/ ' 

^W 1 ^^^^1 

^ r 

— ^y E ^^^^1 

^1 «i 


^fi^^^^r^it *^^^l 





"Ia bI^H 


' l^.. 







! -.'1 n 

* • 


Action of tKe air 
upon tKe inclined 



DirccHon . of TgQvement 


From this point of view, therefore, partitioned 
planes are really superior. 

be "elevating rudder" is a similar device, but 
ing about an horizontal axis, and causes the aero- 
e to deviate, not to the left or right, but upwards 
downwards in its 
3ctory, in a word, 
;h causes it to as- 
l or descend. Its 
ation is explained 
le same manner as 
of the steering 
ler. This invention 
been attributed to 
Wright Brothers, I 

I believe errone- ^^' ^^' ^^® steering rudder 

Yy as Colonel Renard applied it to his airship La 
nee in 1885, as is testified by the official docu- 
Ls published at that time, which contain the full 
ription of the arrangement and also the explanation 
3 working. 

le steering rudder can be placed either at the bow 
;em of the aeroplane ; each disposition has its advo- 
3 and opponents. The Wright Brothers have placed 

the bow, and as people " went a trifle mad " on all 
bore their names, it was concluded to be " necessary " 
it the elevating rudder at the bow, just because 

placed it there. But Messrs. Esnault-Pelterie land 
lot, the constructors of the Antoinette aeroplane, to 
only these gentlemen, instal it at the stem, and it 

moreover, L. Bi^riot who made the first round 
J journey ; it is his name that subscribes to the 


historical page of the first practical application of the 


Every one knows that principle of reasoning, exten- 
sively used in geometry, which commences, when a 
problem has to be solved, by the use of those honoured 
words, ** Let us suppose the problem as sdved.** 

Present industry offers us a number of varioos 
machines which, if I dare so to express myself, ''can 
only go if they are already going ; '' for instance, the 
explosion motor, which must be ''launched'' witii all 
one's might to start and to enable it to assume its 
normal speed. 

The aeroplane is a new example of this method of 
procedure : the conditions of its equilibrium suppose its 
being already started : at rest, it remains on the ground. 
Therefore it must receive an initial impulse, which 
''launches" it into the atmosphere, and gives it that 
speed which, owing to the molecules of air gliding 
under its oblique wings, first lift and then sustain it 
There are two ways of conceiving the launch ; they may 
seek to endow the aeroplane with means enabling it to 
launch itself, in which case it would reaUy be self- 
starting. On the contrary, it may be launched arti- 
ficially with the help of a contrivance remaining at its 
point of departure ; then the launching is easy, bat the 
apparatus if it lands cannot start again, it must first 
return to its starting-point, under penalty of being 
condemned to rise no more into the air. 

French constructors and aviators have courageously 
accepted the hard conditions which an aeroplane must 


^Ifil to be ''self-starting/' and all our aviation apparatuses 
leave the ground by their own means. For this they are 
mounted on a frame- work with bicycle wheels, a carriage 
^which must be as light and at the same time as 
strong as possible, since at the moment of landing, the 
shock of the apparatus coming against the earth, howso- 
ever much it may be lessened through the skill of the 
aviator, falls entirely upon that framework. It is an 
additional load, which may vary from 50 to 80 kilo- 
grammes, which any aviation apparatus desirous of 
launching itself without outside help, must carry with it. 
But there is another extra weight imposed under this 
condition ; it is the increctse of motor power necessary 
for launching, which commences . with a run along the 
ground, under the impulse of the propeller screw 
attacking the molecules of the air. The inertia of the 
motionless apparatus must first be overcome, and for 
this the motor must give a pull "at the collar" 
sufficiently strong to develop an excess of power on the 
part of the motor. This '^ collar pull '' causes the aero- 
plane to roll along the ground, with increasing speed, 
until the latter is sufficient to bring about the lifting of 
the apparatus by the action of the air striking on the 
under part of the wings. Once the apparatus is in 
the air, but little effi>rt is needed to sustain and 
propel it. However, it entails the transport of a 
motor, heavier than was really necessary, but the extra 
energy of which was indispensable for launching. This 
additional weight, in conjunction with that of the frame- 
work^ requires the . " self-starting '' aviation apparatus 
to carry an excess of weight which may vary from 100 
to 150 kilogrammea 


Qaite different are the oonditions of the aeroplaDes 
iviiich are launched in an '' artificial *^ manner, such 
as thoee of the Wright BrothenL Freed from these 
severe conditions, the American aviators have required 
the &11 of a weight for the necessary lannchiog 
effort for their apparatus, and to avoid any exta 
weight, even that represented by the weight of the 
supporting truck, they glide their aeroplane, in order 
to start, along a "rail," attended with very little 

The idea of the launching weight is ingenious and 
effective, as it must impart to the aeroplane an increae- 
ing speed ; now, the falling speed of a weight incresaaB 
exactly in proportion with time ; this is the first kw 
concerning the fall of bodies. This weight, in its fidL 
in drawing the aeroplane along by a rope and return 
pulley system, will therefore impart to it a speed which 
will steadily increase. Relieved of the extra weight of 
100 kilogrammes at least required for "self-starting," 
the aeroplane thus launched can use an ordinary 
automobile motor, a little heavier than the special 
type, but working more regularly, instead of the extra 
light motors used in French aeroplanes, in which, every- 
thing being sacrificed to lightness, there may sometimes 
be defects, especially in regard to endurance. The 
American aviators are therefore placed in better con- 
ditions, and have been able to accomplish feats which 
possibly they might not otherwise have achieved, with 
the same facility, feats limited, moreover, since they 
must land near their launching apparatus for fear of 
being rendered powerless and prevented from starting 



When the aeroplane is in steady motion in the air, 
when it is soaring at its '^ regulating speed/' everything 
is working normally, sustentation, advance, steering, 
in the manner we have explained. But the motor may 
happen to stop, either by the will of the aviator, or 
accidentally. Let us now examine what will occur in 
80ch an event. 

By virtue of its acquired speed, the aeroplane con- 
tinues to advance; but, propulsion failing it, the 
retarding resistance of the air will be felt more and 
more, and its speed will be rendered useless. It must 
therefore, keep it up, and, no longer having a motor, it 
can only do so by descending in an oblique manner 
towards the earth ; then its weight will serve as the 
motor ; in this manner it will reach the soil as gently 
ae the aviator desires. In the descent, moreover, the 
steering-rudder will permit the landing-point to be 
duMBcn, and the apparatus will come down quietly to the 
ground. Thus, theoretically, at least, an aeroplane effects 
a "descent," but never a "fall." This descending opera- 
tion is effected in a ready manner by French aviators, 
who have become clever experts. It is needless to 
lay that the greatest presence of mind is necessary 
to conduct an aviation apparatus; distraction may 
prove fatal. With this presence of mind and skill in 
manoBuvring, " motor failure " is no longer dangerous 
to the aviator ; it only interrupts his journey. 

Many persons ask aviators why their " heavier- 
than-air" apparatus is not provided with parachutes. 
This frequent question is answered fvllj by what 


'6 have just said. It is useless to fit a parachute 
an pparatuB which is in itself the most perfect 

"^ ) V ill now study the practical arrangements of an 
plane destined to fulfil everyday service and to 
possess lualities of safety, solidity, and speed. 



^ 1^ CRV18 : Motors and propellers : Safety : Wind 
N S Btd the aviator : Must we fly high ? 


^3 aeroplane to be provided with a motor 

irr as perfect as possible (we shall go further 

>^on of these two elements) its essential 

^sustaining or supporting surface. This 

*imes called the ''set of sails/' and the 

^r£Bicee are also known as "wings." We 

*& there is an advantage in making them 

era on the under side. Moreover, they must 

^tsverse to the line of travel, whether in a 

^)r a very much opened V. The supporting 

^med of cloth stretched upon a light and 

ra frame-work. The same india-rubber 
serves for the construction of dirigible 
jl^fben used, 
me-work is formed of members which have 
this offers to the wind a resisting surface ; 
latter must therefore be reduced to the 
, in other words, the " power of penetra- 
apparatus must be the maximum. It is 
,ve a heavy piece, entailing a gresst^r loa^ 



to be lifted and sustained in the air, if well thought out 
in regard to its shape relative to the resistance the air 
will bring to bear upon it. 

It will therefore be advantageous to give the sections 
of the parts cutting the molecules of air fish-shaped 
profiles, with the larger end foremost (Fig. 60)l' ITMse 
lines are followed particularly in sections of tiie wings 
of several existing aviation apparatuses ; the wing firtme- 
work is pisciform in section, and the panels of oloth are 
stretched on both sides of this skeleton. 

For this reason it will be necessary to avoid too many 
stretched wires, ropes, manceuvring cords extending to 
the exterior, and cross-pieces ; and if it is remembered 
that biplanes cannot do without the latter, which are 
indispensable for joining the supporting surfaces together, 
it will be understood how inunense is the superiority of 
the monoplanes over the biplanes, at least from the 
nir-roflistance point of view. The latter in their various 
forms, in ])articular those of Voisin and Wright, offer to 
ihd air very needless resistance to advance, as only the 
Hupporting surfaces are efficient. For high speeds, 
which are the aim of aviation, I would therefore be 
tempted to believe in a much more brilliant future for 
monoplanes ; those of Esnault-Pelterie and Bl^riot, and 
tht^ Antoitn'ttc aeroplane already represent more than 
promises ; their first exploits permit one to hope for 
resnlts still more brilliant later on. 

A part from the transveree sections, there is the nature 
and character of the sustaining surfaces to be considered. 
The fabric of which the set of sails is made must be 
stretched upon the frame-work of the wings with the 
greatest care ; the seams, knots, heads of nails must in 





• « a- * « -^ •■ 

Direction of mot ion. 

Fig. 60. Fisciform seotion of 
the wings 


DO way project; the surfaces must realise, as far as 
possible, their geometrical definition, and be of an abso- 
lute continuity and regularity, and the fabric, stretched 
to the maximum, must also be varnished in an extremely 
careful manner. It is these conditions, difficult to fulfil, 
which render the con- 
struction more or less 
valuable, according to 
how it is turned out 
with more or less " finish." 
It is this perfection of 
workmanship which is 
responsible for the relatively high price of the present 
aeroplane ; it is how the French constructors, who have 
carried it to the utmost limit, have acquired a reputation 
which ensures them a superiority which is equivalent to 
a real monopoly. 


Aeroplane motors must be light, and only the explo- 
sion motor, working with the combustion of a mixture 
of air and petrol gas, fulfils the indispensable reduction 
in weight. As early as 1884 Colonel Renard showed 
that if the weight of the motor, everything included, 
was reduced to 5 kilogrammes per horse-power, one could 
realise dynamical sustentation and efiect ordinary avia- 
tion. The colonel's prophecies have been amply attained, 
and even surpassed to-day, because the motor with a 
weight of 2 kilogrammes per horse-power is realised. 
In regard to mechanical apparatus, we are therefore 
equipped for the conquest of the air. 

Nevertheless, too much must not be sacrificed to 

• :r 

titn ^r^^sL fe Tuilihinna^ "Anat jKt dinr ^""^^ It b 

Ji H^s'jui rumsaiB of onMbimiig: wfo^OrvtdmaiaKk m to 
ciitiv^9iiH^ i^'rLL tL vmam ntsftibaoBm ; fivm this point of 
vji^v *mU^ '' nTJfa.iuaL mp&ois ^ -of vbt AwJmMkgUe make, 
Vu'.iM yf JL Zfiuii.iih-'PtLiieraei. IL Beomiilt« mud even 
'A:ji^nt: u-*: ^'j^Si-yr^Lj reoGaricfrble. In pmrticiilar, the 
nt^i'^u of tiie Eezduoh-Pc^usie motor, having several 
*:t^%*\Lk vir^jrk'iTj.^ ^yjL, the same shaft, and actuated by the 
\n^m f^Aa tLirikfigfA in a xadial manner, has ensured a 
fum^fl^rrnlAH rli^crease in weight. One single cam ensures 
iUi: workiuff of the valves. 

ir li^litniTHH is the paramount condition which the 
motor rniiKt fulfil, it is yet inseparable from strength and 
I'ti^iiliit'ity in working. With the beneficial realisation 





of this last condition, it will be possible — it will even be ad- 
visable—to reduce the weight of the motor more and more, 
as absolute safety will only be acquired when it is pos- 
sible, on a given aeroplane, to instal two motors, each being 
of a power alone sufficient to sustain and to propel the ap- 
paratus. Then the '' break-down," the terrible break-down 
which inevitably brings about the descent^ if not the fall, 
of the aviator, will no longer need to be feared ; for if one of 
the motors should fail, the other, already running, may 
be speeded up ; and as each one is, according to calcula- 
tion, adequate to ensure sustentation, a fall will no longer 
be feared. The great development that has been realised 
for some time past in motors permits us to believe that 
this hope will soon become a reality. 

There is another point to which constructors and 
inventors will have to devote attention : this is the 
perfection of the rotary motor. Shocks and unavoidable 
vibrations, due to the to-and-fro movement of the pistons 
in the motors such as are now used on aeroplanes and 
dirigibles, cause the framework to warp and forcibly 
tell upon the joints and bracings. These vibrations are, 
moreover, ^transmitted to the suspension and stretched 
steel wires, reducing the strength of the latter ; in the 
event of a combined efPect these vibrations might even 
bring about a rupture, by a phenomenon similar to that 
which has brought about so many accidents to suspension 

The rotary motor, of which the " turbine " is a t3rpe, 
has the advantage of suppressing shocks. Will it be 
possible to accomplish with the explosion of gaseous 
mixtures, what has been done by steam in turbines? 
It is still impossible to say. But, in any case, the 


eflEbrtB of oonstraoton mmrfe now be tamed to thk 


The only propeller used in aviatiim (exeept intfae tridi 
with omithopt^re apparatus) is the aorew. We hava 
explained its general properties in spealdqg of diiipbb 
balloons ; we have defined its '' j^toh,** «8' weU as Ae 
" slip/' resulting from its workmg in the air. 

But we must return to it a little in (peaking of its 
application to aviation apparatuses. 

We are not at present very well supplied with really 
reliable " data " concerning aerial serews ; the eaLcellent 
works of Colonel Benard lutve cleared the qoestion with- 
out solving many individual points. Experiment akm 
is able to furnish data as to the practical value of a aonw, 
and then it works " at a fixed point/' &at is to say, 
moves upon an immovable dynamometw, which gaugeB 
its mechanical effort. 

This data is not absolutely sufficient, as in aerial work 
a screw does not furnish the same useful eflEeot as when 
working in a fixed point ; in any caM» thia data is 
necessary, and therefore above all tractive expenmants b? 
mean, of. d^naMometer for <»ch <»»w mo^ll^^ 

Once this result has been obtained, a serious ijpjioBtiim 
of vital importance arises, since, according as to Ikiar it 
is settled in one direction or the other, there wiU ranlt 
an aviation apparatus presenting an appearance and 
qualities very different. This question is: Must the 
screw be of a very small diameter, and revolve at high 
speed, or must it, on the contrary, be very large, and 
turn " slowly " ? 



rr^^ I 

1 ''^^ 

M^^^Kt^lb. ilk . 




n i^r' 



These two ways of planning the propeller have given 
birth to ** two screw-propeller schools." Both solutions 
have been experimentecL Large screws were the first to 
be used, especially on dirigibles, and in particular on 
those of Griffiuxl, Dupuy de Lome, and Benard. This 
condition, moreover, was compulsory at the onset, owing 
to the slow revolutions of the motors employed. 

But when the explosion motor, with its very high speeds 
of revolution^ entered aeronautical practice, preferences 
changed, and there was a rush on small screws turning 
very rapidly ; there was a fear that the actual rotating 
speed of the motor would be " reduced," and it was desired 
to govern the screw directly by the engine by mounting 
it direct upon the shaft of the latter. Thus we see the 
Lebaudy dirigibles, the Voisin aviators, the immense 
airship of Count Zeppelin, fitted with small screws run- 
ning at a speed ranging from 1000 to 1500 revolutions 
per minute. 

The appearance of the Ville de Pa/ris and Bayard^ 
Cl&memJb airships, fitted with large screws running at 
from 300 to 400 revolutions only, and especially the re- 
markable performances of the Wright aeroplane, the two 
screws of which rotated at a fairly low speed, has served 
to support those who very justly maintain that the 
employment of screws of a large diameter is more advan- 
tageous. To-day there seems a more general tendency 
in the direction of screws of a greater diameter and 
revolving less rapidly. 

Another question, quite as important, is to whether 
(me or two screws should be used ? 

In principle, two screws, one forming a screw on the 
right, and the other a screw on the left, and revolving 


in opposite directions, are in every way prrferabla In 
fact, with one screw only, the aeroplane tends to indine 
in the direction of its rotation, and its great sur&oe alone 
prevents this inclination firom becoming serioua 

With screws of opposite pitch and direction, these tio 
effects become neutralised, the one tending to incline the 
aeroplane to the right, and the other to the left The 
motive effort is then quite symmetricaL 

But the use of two screws may in certain cases present 

a great danger, and for the following reason : Let m 

suppose an aeroplane provided with two screws (fig. 6U) 

driven by identical motors, or by equal transmission of 

the energy from a single motor ; each has a turning effioek 

following its axis, and as they are placed symmetrically 

with regard to the centre of the supporting surfiau^e, the 

resulting propelling effort is steadily applied at one pomt 

of the symmetrical plane of the whole contrivance. But 

if one of the two screws — the right, for instance— for 

some reason should cease to act (Fig. 61b), either through 

a fracture or failure of the motor-power which drives it, 

the aeroplane is instantly subjected to the action of one 

propeller alone — the left one ; this movement is eccentric. 

The apparatus will, therefore, be subjected to a propelling 

effort which will itself be eccentric, and will tend to 

assume an oblique direction ; it will take it too rapidly 

for the aviator to have time to correct it by means of 

the rudders, and a fall may be the result. This is, 

unfortunately, what happened with one of the Wright 

aeroplanes. Orville Wright, having on board an oflScer 

of the American Army, Lieutenant Selfridge, was a victim 

of this contingency. The aeroplane fell, the oflBcer was 

killed, Orville Wright had an arm broken, and had to rest 



Ox- two long months. The French aeroplanes, perfectly 
*»«)ught out, have never experienced such mishaps. 

!7roin the point of view of safety, the use of one screw 
fclcmo is, therefore, very preferable. If it is absolutely 
. to use two, it is essential that the disconnection 

with two propelliira ; 

tr stoppage of one should stop the other, and with the 
ud of an atUoTnatic arrangement, for instance, the trans- 
mission of the power by a single chain. Under these 
oircumstances, in the event of propulsion failure the 
aeroplane would be in the position of an ordinary " break- 
down/' and must descend by "gliding" upon the air, 
&At is to say, by making an experiment in soaring 

Ijastly, one more doubt may arise in the mind of the 
ematnictor ; must its screw or screws be placed at the 
bow or stern ? Must one, in other words, have screws 
which "draw" or screws which "drive"? Opinions 


' ^ 

anr arrttiijtrenient-f- art aiviaeo xi zn*r apDararjse? r.-^ 

cit ::jih* o^. Bifrioi. Emmuii -Peiteni . tn- smc^ screv s&t 
Hit D'jv ii tii^r Farmaii aeropiart. i: is- a: zut sien^ 
tii»r fc?upporiiij£r BUiiaces thif- L^ alsi tiit- arrriijjr^rc: 
wiuc-i Hit Wrich* brothcTf- iiavt- adoptee: ia: zii^vrf 
b'j!>-\vt wijic'i. art ■■ urivmrr Bcrewfc.' Al uies*- aer'-iiiijiss 
iiavt bijjvi difiert?u*i quaiiiiefc. buT buci. ai^ ait- iii:*ji:=?.* 
aoj*r I: lb liiereiort impoBsibie tc declare o£-iiLi: b 
lfc\'ju? vi oLit o! tbt- otiie:. and tbt- posixioL of zittssref 
wiL Uf ]>fiiC upoL tilt spread, tbe emj>eiiiia£'t:. mj- iii:^ 
o! i»rbfc ibt ioui; itfvtfiifcert- o: iht^ iatte: 


'Jhert ifc. aibo. one pan of tbt aviaxioii apparuTas^A 
>M: iiavt jje^rlecved up zo no v. bui irhicL if ne^srtiftifi» 
JlJUl^^{Jellbable : it ih tbe '* bcidy '" vbicb piays Lbt jiaricJ 
i)j«; ♦;ai of" ibe diriirlble. iba; it xo sbt tbe sDact aesdri'id 
r'j ';;a'tv :.}]*: iiv.iio: . ibe T»roi»eIje: . and The 2iT-i&.T:»r, :Le 


j/ i*J" ili«: aer'^piane. since i; c^niaiiis ibe ir&ve-irr ; it 
fj-o-r ),'am:\<.-i. dinjensions, and bowever ^ir^ali ii iiiavbe 
'!i-^:;'/ii-'l.. x\itih*: cannot b-- aToidtf-i : i: ttIII therefore 
j.M ^'.l jji. lo tij'i air a resisting surfaoe. "wbicb must 1* 
I ;.*!'' fj jfilii a':c"UJit. 

In iIji' \\'ri;/lit JtJi-'.ibers' aeroplanes tbere is no "btHly: 
ii i.'^ H'liir«;(l lo lliut 'jf tbe aviator, sitting over eiiipiv 
hj/jui- ojj ;i l;itticu<l seat, with the feet simply restii:^: 
iip'iij ;i if ohs bar. This is a possible arranijement wiUj 
opiiaidih ah <:l<rver, as '* artistic," as master of their nerves 
ah VVilbiij and Orville Wright, but in my opinion it is 


an arrangement to be condemned absolutely ; aviation is 
already a sufficiently daring form of aericJ travel without 
increasing the risk, by decreasing the conditions of safety. 
!nie Wright aeroplanes moreover have not yet made 
any * 'journey " properly speaking, either in Auvours or 
in Paris ; they always limit themselves to performing 
eivolutionSy sometimes for a long time, above a test field. 
Bat practical aeroplanes able to extend real services, 
saoh as those of Bl^riot, Esnault*Pelterie, Voisin, &c. . . . 
all have a " body " serving as accommodation for the 
ayiator and the machinery. 

This body, thus being compulsory, it is necessary to 
utilise it to the best advantage for the balance of the 
machine. First of all, we must give it, undoubtedly, the 
- ahape of the body of a bird or fish, the large end to the 
jfiront; under these conditions, and if the firamework is 
oarefully covered with fabric tightly stretched and very 
nlooth, its resistance to advance will be reduced to the 
Twiniinnm, This body will, moreover, serve a useful 
purpose; it will increase the resistance on the sides, 
that is to say, oppose *' drifting" and the action of 
centrifugal force when turning. 

Thus planned, the shape of an aeroplane becomes 
eloeely allied to that of a soaring bird. The action of 
the air upon the various parts of this '' body " inust, 
however, be carefully studied as regards stability in the 
direction of travel, and here it is that Colonel Kenard's 
works must be borne in mind. More than ever (as we 
have already said) the empennage is here indispensable 
for securing the safety of the apparatus. 



The real groat advantage of aerqplaiieB in their appfi- 
cation to aerial timTel ia tpeed. 

In all trials wherein somewhat prolonged flights haifB 
been aooomidished, it has heen seen that the present flpeed 
of aviation apparatnses is at least 60 to 70 kilometres per 
hour, and in Fannan's now historical jonrney fixxm Bhdsitt 
to Ch&lons, not only did the daring aviator adiieve 
on his French Voisin-biult aeroplane the first " aeriil 
jonmey '' worthy of the name, leaving a field of experi- 
ments and passing over villages and forests, bat he eves 
made it at a speed of 78 kilometres per hour. No 
dirigible, at least at present, can attain audi a qmd, 
and the speed record in the matter of aerial navigation 
therefore belongs to the aeroplane. 

Can this speed be increased ? 

Not only can it be increased, but it must be increased, 
if it is intended to make really practical use of aviation. 
At an imposing conference held at the French Society 
of Aerial Navigation in December 1908, the engineer, 
M. Soreau, a former pupil of the Ecole Polytechniqae, 
dealt with this question in his highly competent manner; 
he selected as a type a '* family " of aeroplanes of the kind 
constructed by the Yoisin Brothers, and supposing them 
to be all provided with motors giving the same weight 
per horse-power, propellers having the same output, saik 
having the same co-efficient of efficiency he showed that 
the useful maximum weight would be obtained with an 
aeroplane having dimensions only 10 per cent, heavier 
than the original aeroplane ; but its speed must be treble. 


that is to say must reach the figure of 180 to 200 kilo- 
metres per hour. Now the '* useful '' weight would reach 
one ton« M. Soreau has arrived at analogous results by 
studying a ** group** of aeroplanes of the monoplane type 
constructed by Esnanlt-Pelteria 

But, when our ''artificial birds'* will have realised 
such speeds, when ihey will have to carry such weights, 
it will no longer be possible to be contented with this 
construction of slender firame-work, a marvel of lightness, 
certainly, but not sufficiently solid ; it will be neceasary 
to make all its component parts very strong, and to 
enable them to resist even the greatest strains to which 
they may be submitted. Let us cite here M. Soreau's 
important conclusions; ''aeroplanes of large carrying 
capacity will have to be very stoutly built, not much 
larger than the pres^it, at least for the next few years to 
come, but their speed will have to be double or treble that 
in vogue to-day. Now, for these new machines we shall 
be forced to employ other materials ; it will be necessary 
in particular to attend to the reduction of their resist- 
ance to advance ; in short, it will not be sufficient to be 
content with constructing aeroplanes based strictly upon 
the present apparatus. These new apparatuses, so soon 
acf they are perfected and have received the sovereign 
sanction of experience, will thus become the first aero- 
planes of a new fiEunily, and so on." 

Aviation apparatus will therefore be perfected by 
evdiution, which is the case in nearly all the great 
developments realised in physical science or applied 

What must be remembered in these conclusions of one 
of the cleverest aeromechanics of to-day is that before 


loog« eweu rerj dxtlfy, we AaSSi mit umfu^ obot mamd 
200 kilometres per boor. Thm k ^woll te* tDriikr 
to my that "^ dittJUjce do hmget 


Wtiat we have said regai&i^ ttiie* acsaift af ik 
wind upoD dirigiUea appfiea f|«ill1hr w«ill i&» arisai 
apfmmttia; ''Wind doea not cxitft iar tiie mto^^ 
which niovea in tlie KUwkompktre; it ia as if tfcs 
fiptiere were immovable ; the wind oaij taoM 
of the aviator changing poaition m rela&M ndk tic 
yroufid beneathJ' 

We ahall conaeqoently have to rwiilfi the 
valuea in aviation aa in aeronaaticiL If the 
M{>eed of the aeroplane ia leaa than that of the wind, it 
will only be able to approach the points of the spat 
contained in the interior of a certain " afyroachaHc 
un^li5 ; '' if itH independent speed equals that of the wind 
it will l>e uble to approach any point to leeward of the 
lino pcrponclicular to the direction of the wind at its 
|H>hiliori of departure ; lastly, if its independent speed is 
gt'Daior than that of the wind, it will be able to go any- 
whnrn. In all cases, its speed is governed by that of 
Miti winil to give its resulting movement. In an extreme 
r.ann whoM it navigates exactly with '' wind behind,'' its 
h|MM«l (if travelling, with regard to a fixed guiding-mark 
(.iilinn on land, will be equal to the sum of the speeds of 
tho wind and of the aeroplane. It will equal their 
diirnrnnco if the aviator navigates against a '' head wind.' 
Att to-day the speed of 78 kilometres per hour is reached, 
it in NiHin that, at present^ an aeroplane may travel, in 
iWiii, on an average 352 days out of 365 ; when a speed 


of 150 per hour is reached, it will be possible *' to go out 
every day." 

I ina^t meet particularly upon this notion, as it is 
often distorted or acquired in an incorrect manner. 
Thus, if an aeroplane is going in an easterly direction 

FlO. 62. Combiaed actJOD of wind uid propuUion gprada 

in a south wind of 20 kilometres per hour at a speed of 
60 kilometres per hour (Fig. 62) it will effectively navi- 
gate with a speed of 60 kilometres per hour ; but the 
" section of atmosphere " in which it will have effected 
these 60 kilometres will be displaced towards the north, 
by the effect of the southerly wind, by 20 kilometres ; 
the aeroplane will then have followed an oblique trajec- 
tory, represented by the diagonal of the parallelogram 
constructed with the help of two speeds, its own inde- 
pendent speed and that of the wind. 

This conception may even be *' materialieed," so to 
speak, in the following manner. Let us imagine an 
enormous aerostat, formed of a perfectly impermeable 
envelope, aud maintaining its equilibrium high in the 
air (Fig. 63). We will suppose that this balloon has 
dimensions sufiSciently large for an aeroplane to be able 
to describe evolutions in its interior atmosphere. This 


atmosphere will be forcibly sheltered from the actioo of Uie 
outer wind, since it is enclosed in an air-proof env^<^ ; 
the aeroplane will therefore mancenvre in still air, and wiD 
go from A to B, but during the time it takes to aocotn- 
pliah this journey, the whole balloon has been trsns- 

Fio, e3. Wind aod tb* aeroplaae : kctu&l uid ceUUve routea rMpecttnlj' 

ported by the exterior wind from (l) to (2); tba 
aeroplane has therefore duly arrived at point B, hot 
this point B has been transported without the aviator 
being aware of the fact to B' ; so that he will bava 
no longer below him the part of the terreBtiial sur&ce 
which was below point B, but really that which ms 
below point B'. Let us now remove in thought the 
envelope which isolated the interior atmosphere of the 
aerostat ; nothing is changed in the general conditiona, 
but we can thus understand tiie true road of the 
aeroplane, AB'. 



The height to which it is advisable to rise to practise 
aviation is intimately connected with the conditions of 
safety l«d down by the aviator. 

At first sight it may be imagined that it is essential 
to decrease the risks of accident by navigating very 
closely to the ground, to sweep close to the earth like 
swallows because, it is thought that " if one fall, one 
will fall from a lesser height." 

This reasoning is admissible for risks entirely " experi- 
mental," when one is not quite sure of the stability of 
the apparatus in which one is to ascend. But once this 
apparatus has been tested, and once the efficiency of its 
equilibrium has been ascertained, it is necessary then to 
avoid too close a proximity to tbe ground, and to navi- 
gate at a certain height, say, at about 1 00 metres. 

As a matter of fact, let us consider what takes place 
in tbe immediate neighbourhood of the ground (Fig. 64) ; 
the moving molecules of the air, the horizontal dis- 
placement of which constitute the wind, are forced, 
when brought into immediate contact with tbe terrestrial 
surface, to follow all its superficial variations and to be- 
come deflected by its projections. The gaseous molecules, 
approximate to tbe luidulations of the ground, will thus 
follow at one time an ascending, and at another a descend- 
ing path, and if their speed is of little consequence, that 
is to say, if tbe prevailing wind is not very intense, 
these inflections of the currents of air cause " ascending 
winds" and "descending winds," as is illustrated in 
Fig. 64. 




It* lir uia nittn lianriaamailjr \t^- itsh ^mi^p^. 

uu«/\|>iAitft iTuinit;. uut; .« giiwih^; in time in. Lm^ diilihc ^ 

•mtifffaiiifflO iif i&t-aiir 


w^^.^ .*j:t ^•. ';■<: . *:.!* "w-oiijii zriirsLZ. It ripoi fill i.-^.. .rertAin 

t.,//;. ;a^ or.<: m^ iT. tLe &^, a::<i a: a certain height, as is 
:y>trf» .f. '/-if ftlct^ch, ihe siThtJdk Krf iiT become steady and 
ft',yr t!. ?k \tnn7/juX;iA iriar^ner, beoig solely quickened by 
»,J,//c;rfT ''ufi/iul;»Viry rrjovemei^ts ' so ingemously described 
Sfy M. H^nf:i±n. C'>n?>equently it will only be at these 
ol».ii'j'J«5ft that the aviator will be sure to find the normal 
Kiors; of th'j atmosphere ; it will be at these heights that 
\t^. will have to fly if he \*Tshes his aeroplane always to be 
** III Um: happy medium " for which its various elements 
wtrr^ tmlrAilathd : lastly, it is where, in the event of 


a breakdown to his motFor, he will be able to commence 
the "gliding" upon the air, which, with a Bearing 
flight, will carry htm harmlessly to the ground, whereas 
he could not effect such if he were struck by a current 
of ascending air which would capsize his aeroplane and 
infallibly precipitate a faU. This descending glide will 
be effected with the greater safety inasmuch as it 
will commence higher above the ground, and also 
because the aviator will be better able to select bis 

Nevertheless, I believe that very great heights are 
impossible to aviation : the too rarefied oxygen would 
be insufficient for the combustion of the gaseous mix- 
ture, the explosion of which constitutes the motive 
power, and the supporting surface, as a result of resist- 
ance to a thinner aii', would no longer be adequate 
to ensure sustentation of the aeroplane, which would 
become unstable. These objections do not exist with 
average heights (from 100 to 300 metres) which are 
easily accessible to an aert)plane ; at 100 metres altitude 
the supporting power of the sails of an aeroplane is only 
reduced, on account of the decreased density of the air, 
by l>80th of its value at ground level. 

This question of safety is closely connected with that 
of landing, and the latter is, as may be easily understood, 
of the greatest importance to the aviator undertaking 
an aerial Journey. " It is not all skittles, I must get 
out of this," said La Fontaine's fox ; it is not only 
flying, one must regain the ground, and return to it 
without breaking one's bones. 

Now» calculation, and calculation based upon experi- 
moital data, shows that for a given aeroplane, there is 


nodw pow neeenuy to obtain the 
So ooQB ao a notifo powor oacooed* 

ing tho mnunum is braopifc mfco Iwyy two ittulti 
aiid, eonnqiMailf , two ^peadi ore poanhfe. Thoa^ifve 
hftTO a motor the powar of whidi ar ge a e c la the minimiim 
apead bj 4 par eent, the two apa a da wiB, one of theai, 
be 16-lOOdia in exeiOB^ and the odiar 17-100th8 laaa thu 
the goraming apead, a c c ot din g to the ineKnaticm of the 
aaSk If the motiTe powar a »e e adi the mjnimnm pomr 
hj 15 per cank^ the two poaaiHe apaada aie^ the one a 
third in ezoaaa of the Beeeaaaiy qpeed, the other ooo- 
qoartv ]aaa» according to whether the aaila are indined 
mora or laaa bj the aetion of the elarating rodder. 

Since it ia thoa poatibie^ bj maana o£ a aligfat exoM 
of power, to have two yeda at diqioaal, it will be 
poasiUe, aa the oiginear M. Soreaa remarked, to nae tbe 
greater for the ''travelling apead" <^the awoplane, and the 
lesser one for landing, which will thns be effected without 
danger, for when the apparatus has approached close to 
the ground, the fall caused • by the excessive inclination 
of the sail will be appreciably deadened by the '' mattress 
of air " interposed between the ground and the support- 
ing surfaces. It is then, in coming into contact with 
the ground, that the mechanical absorbers, on which the 
wheels of the launching rolling-chassis are mounted, 
become indispensable. The landing of heavy aeroplanes 
undoubtedly will require elaborate precautions, and will 
demand on the part of the aerial pilot extreme cleverness 
and presence of mind. 

How may accidents arise ? From two different causes 
— the sudden stoppage of the motor, or the breakage of 
one of the essential elements of the aeroplane. This last 


poBsibility can ecarcely be admitted, since, if the aero- 
plane is well planned, carefully constructed with first- 
class materials whose strength has been thoroughly deter- 
mined by experiment, if, moreover, before each ascent 
all parts of the apparatus are carefuUy examined, and 
the mounting, connection, and assemblage have been 
inspected in detail, when built, the unexpected 
breakage of any essential part should riot develop. But, 
you will say, there are the road accidents 1 No, not in 
aviation; for on the "highway of the air" there are 
neither shocks, bumpings, nor collisions to be feared, at 
least not at present ; this road is wider than those which 
traverse the earth in all directions, and there is not only 
more room to pass others on one side, but it is also 
possible to keep clear of them " above or below." More- 
over, at pi-esent our aerial roads are not overcrowded. 
Again, the governing speeds not varying very much, the 
movements of the various controlling mechanisms will 
not be subjected to much variation. 

There remains failure of the motor ; but we have 
pointed out, in speaking of explosion engines used in 
aviation, that their continuous development will bring 
about the desired reduction in weight. We shall, 
therefore, very soon have motors at our disposal, the 
weight of which will be sufficiently reduced for it to be 
possible to place two weighing no more than, and each 
of the power of, the single present machine ; that is to 
say, each sufficient to sustain and to propel the aero- 
plane. Under these conditions, together with a device 
automatically setting the second motor in motion in the 
event of sudden stoppage of the first, engine fiulure is 
no longer to be feared. 


dufjoram iypv IwhiMi ^wbon isub obbobb^ 'wdd bi 
iMJBiraonSy if nrt ii'MipHi unb dngflc, «8r mbotwwoi^ 
owijDigto liie tnei^'ivladi wiiuM fnvefe njpijteik 
fMHimgvw aad pfove dEoMHoMi te Ae 

globe ** wliidi cfiba dMiger: w Hj e a Aie 
onmitor The kig e gui& ce rflfap w Mg 
prerant Che appantas wmmmBatdf Anderingp hft 
the aTiiAor, pimied uder Ae plnHS aad *' flmgh d'' 
in Che eaib, imj eolf be dUe te free \ammiM tnm ib 
ropae with difficaHy. ft wS Uiuwiau be «dl to 
proWde eerapleiiee inteBded fiv bng jomneye urttk 
q[i6Ctil flubly OMiltivmeBi^ n inew ef deeooot ipii 

^ Aioeideiito" imdoiibliedlj ^vOl faeppen. odoobtoiflr 
there will be deriog pioiiean of die air who mantHmm 
will pay with their lives their dashe to eoQie another 
victory over the Uxces oi Natnre ; but have not all die 
conquests of human genioB — navigation, raOways, the 
motor-car, even cnrrent industry — beai made at the 
cost of heavy sacrifices 1 And are not the *' acddeDts" 
of daily life as fi>rmidable as those to be feared in the 
new method of loccmiotion, which will^ however, be 
attended with less mishap, because, having the repotar 
tion of being more dangerous, it will be practised with 
greater care ? 


At the commencement of this study, we said there 
vere three classes of apparatus '' heavier than air." We 


have inveatigated in detail those which so far have 
given the most practical results — aeroplanes. It now 
remains for ua to speak about the other two. 

The first is k^icopth'es, that is to say, apparatuses 
which sustain themselves in the air, not through the 
vertical component of lur thrust upon a moving surface, 
like kites, but by the direct sustentation ^ort of a 
motor-driven screw, with horizontal blades revolving 
about a vertical axi& 

It was the h^licopt&re which first haunted the imagi- 
nation of aviators. As &r back as 1852 Ponton d'Am^- 
court and de la LandeUe, infused with the enthusiasm 
of Nadar, the celebrated photographer, maintained by 
Press campaigns, conferences, and publications, that the 
future of the " heavier than air " machine would be by 
meana of the screw — the " sacred screw," as it was called 
by Ponton d'Am^court. Their scientific support was 
Babinet, a membw of the Academy of Sciences, and 
he it was who found the name of "h^icopt^re" for 
baptizing the apparatus which he thought would realise 
the definite conquest of the air. 

What gave weight to the assertions of these tireless 
apostles was the popular success of fiyiog toys, real 
miniature h^licopt^es, which went up in the air with 
the greatest ease, either through the effort of twisted 
india-rubber, or when launched by uncoiling, a string, 
and seemed to defy gravity and to open to all the 
" highway of the air." 

Intellects were fired ; controversies furious ; a study 
was made of the manner in which the screws must he 
arranged. To avoid the rotary movement . which one 
single sorew imparted to the body of the apparatus. 


fixned of • aDMll tttmm 

9U9WM nww^nBg ID DfpiMlB oneboBB abptit tll6 I 

borixontal UEUL ABdwhAeapCteoBnafind orplaimBd 

hitherto oomprue the me of an ecat nnmber of Miein 

of coDtrary pitch, reivolTiiig in c^posite direetians to one 


Experiments were made with h^lici^itbreB, and with 
little miccefls; why is known to-day; the inot<Hs used 
were too heavy, and the intimate diacnanon at the 
problem, made scientifically hy mathematicians, dis- 
onraged investigators from embarking cm these lines for 
a long time, until Colonel Benard tackled the qneetaon, 
wliinh, as usual, be enlightened in a new manner hj 
publishing bis works on suttcUmng tcrewM. 

Cr^lonel Renard, in a communication which he made 
Ut the Academy of Sciences at the end of the year 1903, 
f{iive the results of his long researches, carried out at 
Ohalais-Meudon, on screws employed for lifting a certain 


-. r 


weight directly firom the ground — ^that is to say, with 
'' sastaining lEtorews." Abeady he had previously de- 
monstrated that aerial navigation by aeroplanes would 
be possible the day when the weight of the motor 
went down to 5 kilos per horse-power. Directly attack- 
ing the case of the h^licopt^re, the learned colonel 
showed that the maximnni weight which the screws of 
this apparatus were able to lift increases inversely to 
the sixth power of the weight per horse-power of the 
motor employed. This result strongly encouraged h^li- 
copt^re inventors, but we must reckon not with theoretical 
^* limit " loads, which it would be impossible to exceed, 
but with the real loads compatible with the resistance 
itself of the screws. Under these conditions a really 
transportable load limit is quickly obtained, and these 
loads are lighter for the h^licopt^re than the aeroplane ; 
hence the very legitimate enthusiasm which has been 
manifested in this apparatus. 

Colonel Renard, however, did not leave the question 
of screws, and even indicated in 1904 sustaining screws 
of 2*50 metres diameter, of perfect resistance, not liable 
to distortion under the effect of thrust, although their 
total weight was very small ; he obtained this result by 
introducing a universal joint which permitted the screw- 
shaft to assume the resultant direction of the various 
efforts operating simultaneously upon it. 

Amongst the various dispositions proposed for heU- 
eoptkreSy there is one which has been realised under the 
auspices of H.S.H. Prince Albert of Monaco, which was 
conceived and constructed by Engineer L^ger, and 
whereof Fig. 26 shows the principle. The two screws 
of opposite pitch, turning in opposite directions, are 

Fio. 65. Principle of the L%er 


mounted upon two concentric axes; this axis being 
vertical, lifts the car itself; but, if the axis is inclined, 
as shown in the figure, an oblique movement through 
the atmosphere must be obtained. 

A composite solution was jnoposed, one of which 

Colonel Benard himselt 
had thought ; it is an 
apparatus which would 
be hSliocaptire for lift- 
ing itself off the ground, 
and would become an 
aeroplane once in the air. 
Such a solution, if it were 
ever realised, would be 
that much sought for, 
as the great disadvantage of aeroplanes is the'neoee- 
sary space for ''launching/' So long as one remains 
on level ground, or even so long as there are broad 
roads, this is still feasible; but in wooded or moun- 
tainous country a landed aeroplane will no longer be 
able to re-start, whereas with screwj and vertical axis, 
which would lift it " straight up," departure would be 
easy, and once lifted up in the air, the apparatus would 
have the advantages of an aeroplane. It is to be hoped 
that serious investigations will be made in this direction; 
they will constitute a great development and perhaps 
even the future of aviation. The "gyroplane," of which 
we speak later on, is the first step in this direction. 

Omitfioptires, those apparatus vnth flapping wings, 
seeking to imitate exactly the process of lifting and bus- 
tentation which characterises the flight of birds, have 
been less tested than helicopteres. The difl&culties found 


in their construction are so much greater, and the vibra- 
tions and shocks to which their framework would be 
subjected would not fail to tell on the joints. Despite 
these difficulties, a Belgian aviating engineer, M. 
Adh^mar de la Hault, has sought to realise an omithop- 
tire, of which we give a few photographs ; the apparatus 
was able, in the latest experiments, to rise slightly and 
to leave the ground for a moment, but an accident to 
one of its parts interrupted the trials, which will be 
resumed later. 


There remains another composite solution for us to 
Bpeak about, consisting not in the combination of two 
systems of aviation, but a balloon and a soaring arrange- 
ment, a solution which recalls that of sailing-vessels 
known as « auxiliary " engine vessels, often used in trade 
Euid pleasure navigation. 

Its inventor, M. Capazza, one of the French aeronauts 
who has had the finest '' aerial " career (he was, in fact, 
the first aeronaut to cross the Mediterranean in a balloon 
Grom Marseilles to Corsica, which has not yet been re- 
peated), conceived an immense aeroplane, but with its 
sustaining plane lighter than air. For this purpose, M. 
Capazza took a balloon, not of the ordinary spherical 
or pisciform form, but having the flat shape of a pendu- 
lum-bob. This is not symmetrical, however, as regards 
its centre ; it is not a '' surface of revolution," its greater 
thickness is brought to the bow, so that, cut in the 
direction of its axis, its section is that of a fish (Fig. 68). 
A longitudinal empennage forms, above and imder this 


envelope, a kind of amall wing, a " keel " which oootri- 
butas to stability, which will be still more increased hy 

Stern, motcr 

Fia. tIL Bids etavktion of the Capana tantlonlar bkllooa 

an horizontal empennage at the stern. Besides, the whole 
of the stem part of this pendulum-bob, thinned to its 
back edge, constitutes a marvellous natural empennage. 
The total capacity 
of this bob is to be 
15,000 cubic metres, 
and will be rein- 
forced internally by 
metallic circles ; it 
will carry a car in 
which will work three 
motors of 120 horse-power each, driving three screw- 
propellers ; the weight of the car is carried below the 
greater thickness of the balloon, i.e., well forward of the 
centre of the hob, as is shown in the diagram. The in- 
terior metallic circles distribute the load upon the whole 
surface of the envelope. 

Fio. ET. FroDt view of tbe lenticular balloou 


The apparatus, at first si^t, most therefiure work like a 
dirigible; Imt, on acxxMmt <^ the flat and non-symmetrieal 
shape of the mvelope, it will possess special fNroperties. 
Let 08 imagine a movement of ascent or descent being 
imparted to it ; the apparatos will immediately become 

Circular metal stays 




Fio. 6S. Plan of Captiia's lenticalAr balloon 

lined, as the two areas, that of the bow and that of 
the stem, will be unequally pressed by the air ; the back 
area offers a greater resistance to ascent or descent than 
the front If, for instance, the movement is an ascending 
one, the back part will be depressed, the bow will rise 
up, and the movement of vertical ascension will find 
itself transformed into an oblique displacing movement 
towards the bow. The screws add their propelling action 
to what is thus obtained, and contribute, according to 
the classic expression of artillerymen, to ^'extend the 
tn^ectory." The direction of the balloon becomes the 
more horizonal as its independent speed increases. 


Let vm now wi|ip oBB that ai a grvan momflnt the total 
w^;fat of the mfpeiataa^ envekq^ car, moton, pasBen- 
gera, and eaigo^ finr aooM reaaon or another, escoeeda the 
weight of air diaplaoeiij either heeaoae the lenticukr 
baDocm in riaing haa gone heffond ita acuie of eqnilifannm 
on aooonnt of ita aoqnired qieed, or beoanae phyaicalty 
the inner gaa haa oontraeted, whidi the ballonnet wOl 
have replaced with air : the balloon will immediatdj 
tend to deagendy bat an inyene phenomenon will oocor. 
The greater aoiftoe of the atem part wiU lift it, and the 
balloon will become inclined; it will go down, bat 
in gliding in an obliqne manner npon the moleculeB of 
air in the manner of an aeroplane, will utiKae this da* 
acending movement to progreaa horiaontally. Thia eftet 
will be added to the apeed imparted by the acrewsi the 
propelling force of which will thna be increaaed by auo- 
cesaive aacenta and deacenta. 

Such is this ingenioos apparatus, which ia so ori^al 
in its conception» and which it would have been impos- 
sible to let pass without saying a few words about it 
It would be very interesting to see it realised, for, 
independently of the services which it would render as 
an airship, it might become a veritable experimental 
laboratory for eveiything concerning aviation. 




French and American dcuon: The Voisin and Wright 
aeroplanes: Comparison or their EFFiciENaEs and dis- 


Ws will now describe^ somewhat more in detail, the various 
types of aeroplanes, at all events, those which have accom- 
plished brilliant performances, and consequently have 
thereby demonstrated theactual existence of their efficiency. 
And it is necessary, in all &imess, to begin with the admir- 
able aeroplanes, swift and sure, built by the Voisin Brothers, 
the eminent French constructors. Their name, as a matter 
of fact, is inseparable from those of the audacious sports- 
men who, in France and consequently in Europe, definitely 
opened the highway through the air by their magnificent 
achievements : I mean Messrs. Henri Farman and Leon 
Delagrange. The details given in the preceding chapters 
will enable the reader to appreciate and compare better 
the different machines which we will now successively 

The Voisin aeroplanes are of the "cellular" biplane 
type, that is to say, between the two parallel supporting 
surfaces which constitute the sails or planes properly so 



ealled, ara Tertaoal wiQii foroMd of fiibm i^^ 
the croea iii«mbeni» daugmd to oppooo latenl domticD 
and to maiiititiii aotonu^Mlly the oqmHbriiim ci tiia 
aorcqplaiie in torning, Tho genmal amiigQiiient of thk 
gyatem is shown in Fig. 80. 

The design oomlnnes stre&g& and lig^toess. Uio 
wings axe c^ india*rabber dieathiis^ stretdied xjcpoa i 
diagonally-braced ashwood frame. The i^pread of ^ 
wings is 10*20 metres ; their d^th 2 metres ; and of tbi 
" stays'* whioh yertically maintun the distance betwesl 
the two supporting snrfiioeSi 1*50 m^tees. These sorfiMM 
are slightly curved, the ccMieaTe &oe bdng presented 
towards the earth. When the i{^paratus is in fli^t^ tiit 
*' diord" of the arc formed by ^ profile of the wingi 
makes an angle varying from 6 to 8 degrees with the 
horison. Hie sur&ce of this flai&e ii about 40 squiis 

The whole of the supporting surfaces, called the 
" central cell," has a stabilisating apparatus or " empen- 
nage," comprising a *^ rear box " following also the form 
of a biplane, of less spread than the central cell ; 3 metree 
only by the same depth of 2 metres, spaced 1 *50 metres 
apart, and curved like those of the principal planes. This 
rear cell is placed 4 metres behind the central cell : and 
between its t^o surfaces is placed a plane moving about 
a vertical axis which constitutes the steering rudder. The 
superficies of this rear cell is thus 12 square metres, 
which brings the total area of the planes to 52 square 
metres. The "body" of the aeroplane is a wooden 
framework with cut-water or wedge-shaped ends covered 
with carefully stretched canvas. Its greatest width is 
75 centimetres, length 4 metres. The seat of the aviator 




aced that the centre of gimTitj whiea he is seated 
point which extends Tcrticallj 25 centimetres from 
nt edge <^ the mtpportiDfr sar&oe ; in front of the 




Fio. 69. The Voiflin aeroplane (H. Farman's type) 

'e placed the wheel and the pedals controlling the 

body supports the elevating rudder composed of 
irfaces projecting on either side of the prow and 
^ upon a common horizontal axb. Their shape b 



plane-conyex, the plane being always turned towards the 
earth, the convex aide to the sky. 

The engine is an eight-cylinder ** Antoinette " motor 
developing 40-50 horse-power ; it weighs 80 kilogrammea 
It is mounted upon the frameworiL in such a way that its 
centre of gravity is a trifle forward of the rear edge d 
the supporting surfaces. 

The screw-propeller is double-bladed ; it is placed 
astern of the central cell. It is built up of tubes of steel 
covered with sheet aluminium. Its diameter is 2 metres ; 
it is coupled direct, without any reducing gear, upon the 
motor shaft, and runs at a speed of 1050 revolutions per 

The whole is carried upon a rolling-chassis built of 
tubular steel having four pneumatic-tyred bicycle wheels ; 
those in fix)nt which directly support the central cell and 
motor are of 50 centimetres diameter ; the rear only of 30 
centimetres diameter. The total weight of the apparatus 
together with the aviator is 530 kilogrammes. 

Such is the simple and solid aeroplane with which 
Henri Farraan has demonstrated the prowess of which 
we spoke in relating the history of aviation. This aero- 
plane has undergone some modifications; its pilot has 
fitted a third surface above the first two, thus converting 
it into a '* triplane " ; but the enthusiastic aviator seems 
to have renounced this adjunct, and to have reverted 
apparently to his original biplane. This machine attained 
a speed of 70 kilometres per hour in the journey from 
Ch&loDS to Rheims, covered at an average height of 40 
metres (27^ kilometres in 20 minutes). 

The Delagrange aeroplane (Fig. 70) vividly recalls the 
Farman aeroplane in its broad lines, which is not surpri- 


*. » 


teeing that it came from the workshops of the ssme 
QctoTB, save that thore are only 3 metres between 
ntral cell and the rear stabtlisating oelL 





Fio. 70. The Voitlo Mroplane (Delagmige type) 

nng given the details of the Farman aeroplane, 
iagram sofficiently explains itself, but for which 
or details of the Delagrange aeroplane may have 
lecessary. Its total sarfiu» is 60 square metres, 
t has attained with a SO-horse-power Ant<nnette 


wmd m. acx«w of S'lO BMHtrcs tisanaeier, & epefd i^ 
I per boar. Its totel we^i k 4^0 kikr 
It was Jikeww 'opsi u aempliBk bitih by 
T«iM aad drireo bj & 50-botae-pow c r A ntnipeit e outK 
liMtlI.&pfel. one of tiie joqpgCBt F r mel i aTwb)n,vKiI 
toBflrib tn l&OB, and carried ottt some vcayoselal i^ 
Ihb ax|MniDeota ; Uie higb rtaDdazd of tbft cngiiie u^ 
Ab wmfeteocy of Uie aviator were lugfaly ■{^vecuted 
hf dw Berlin pablic, who fiv the fini tiiao witnesMi 
tntim wilfli a heavier than aii ^jparatu. 


We Wre Been a remarfa ble biplane aerofdue of 
n«Mh flftnstrucdoD which f Els automatic stability, be 
it loDg^dinal or lateral. 1 t os now give, with some 
Artaflff. a deacrtptioQ of t famoas aeroplane irlucli 
ereatod irideepread eDthiudasm daring the sonuiiar of 
1908, and the prowess with which (we are apt to forget, 
petiiapa a little too quickly, this attribute of the Freocb 
aTiaton) would seem to open decidedly the "path 
through the air." We will compare the Amencan 
aeroplane with those which we have already described. 

The aeroplane of the brothers Wilbur and Orville 
Wright is, like the Yoisin aeroplanes, a biplane, with ao 
elevating rudder in &ont and a steering rudder at tbe 
stem. Its main feature is the absence of a fixed stabili- 
sator. Tbe " foundation," that is to say the total length 
of tbe syBtem longitudinally, is 9 metres. The two 
surfaces of the biplane have a spread of 12'50 metres 
each, by 2 metres breadth. The fabric of which they J 
are made is stretched to the maximum upon tvo wooden 
frames formed of two longitudinal members strength- 

P««ll«...' ElevaiiniS plane 

(R-ont elevaiion.) 

3 =i'"»'>»8 

'^ -udder. 



ened by a serieB of transvene pieoe& Each of the latter 
is doubloi and formed of two incurved laths, which are 
kept taut by wedges at the stenL This hi^tter, vetj 
fine, very thin, extends to the rear part of the wingB 
a certain elasticityi a sufficient suppleness, to fiudlitate 
the " warping/' by which means the celebrated Ameiicaii 
aviator secures the lateral stttbility of his aerial vehida 
Steel wire stretched diagonally ensures the indefonn- 
ability of the wings. The &bric is riveted to the fitmt 
edge of the plane members ; at the back, to secure ths 
finest possible finish, they are sewn together. The two 
planes are 1*80 metres (6 feet) apart, and this spaeiii^ 
is secured by vertical bracings, some of which are rigid 
and others articulated. Those of the centre, by meani 
of diagonal supports, constitute indeformable paraUelo- 
piped^, in such a way that those of the extremitieB, 
fixed to the wings by screw rings, are able through the 
articulation to submit to warping which will deform the 
extremity slightly. 

The planes rest upon two skids which form a kind of 
sleigh, because — ^it may be necessary to point out at 
once — the apparatus of the brothers Wright is not sd/- 
starting: there is no rolling-chassis to give it the 
impetus to rise. 

This latter is artificial, and requires an extraneous 
force. These skates act as the part of the apparatus 
which is brought into contact with the earth in landing ; 
furthermore, they are curved, like those of sleighs which 
travel upon the ice. 

The skids form also the ''foundation" of the aero- 
plane ; at the front they carry the elevating rudder, and 
at the stern the steering rudder. The Brothers Wright 


have adopted an elevating rudder very similar to that 
laid out by Colonel Renard, which he used for the first 
time on La France in 1885. They have set it in such a 
manner that its concavity may be varied as desired by 
the pilot in synchrony with the movements which he 
may have to give to the aeroplane. The inclination of 
this rudder is controlled by a lever which the pilot holds 
in his left hand. 

The steering rudder, comprising two vertical planes, 
is fitted at the stem. As the principal biplane is not 
divided into compartments, and there is no cellular 
stabilisator, the action of the rudder would be futile, 
and turning impossible, if the inventors had not dis- 
posed, between the two surfaces of the elevating rudder, 
two small vertical planes which help to support the 
whole system when turning, and to enable the rudder to 
move efficiently to turn the aeroplana The two planes 
of which the rudder is composed are 1*80 metres high, 
60 centimetres in breadth, and are spaced 50 centimetres 
apart. The rudder is operated by a second lever, having 
double articulation in this case, held in the right hand 
of the aviator. 

Thus, the pilot seated on the edge of the under fi:ame 
(the Wright aeroplane has no ^' body "), his feet upon an 
open foot-rest, as is plainly shown in the photograph 
(Plate XXIY.), holds a lever in each hand ; with the left 
hand he inclines as desired the elevating rudder to cause 
hb apparatus to ascend or to descend : with the right hand 
according to whether he pushes the lever backwards 
or forwards he can make his machine turn to the 
right or left. But, in addition, he can give this, 
lever an independent sideways movementi whereby 



he warpB the wings at will. We will see by what 


Fig. 72 shows in detail the whole mechanism for 
warping the wings, when be moves the lever L' on the 
left-hand side of bis seat A. In the case of the diagram 
we suppose that the lever L was pushed towards the 
left a& shown by the curved arrow. Instantly the 
square bent-end m, which answers this movement, is 
turned also to the left and pulls in the direction of the 
arrows the controlling wii'es which are on its right : it 
thus depresses the right-hand rear comer of the upper 
supporting surface. This pomer in depressing also 
pushes downwards the rear right-hand corner of the 
lower plane by means of a rigid and articulated member, 
which maintains the distance between the two planes. 
This right-hand rear comer in depression pulls the 
cord, which is on its left, in the direction indicated by 
the arrows, and through intermediate pulleys raises the 
rear left-hand corner of the lower supporting surface; 
the latter in this operation raises by means of the 
spacing member between the planes the left-hand corner 
of the upper plane, and so is obtained the warping 
which will cause the aeroplane to turn to the left. In 
pushing the lever L' towards the right, the warping 
action is reversed and tends to incline the aeroplane 
towards the right. The same lever L' controlling aJao 
the steering rudder by its movement to and fro, com- 
pensates through the play of the latter the irregular 
rotations which might produce warping. The total de- 
pression of the extremities of the wings by the warpiug 
action Is about 1 foot (30 centimetres). 

A cursory glance at these two levers the aviator holfis 


« what prodigious sangjinoid^ what 
9 must have: a fiJse movement, a 
ion in this aeroplane, having no 

Angle lever 
J^ connecHon 




^ Comer elevsJed. 




\ Gonnecttt^ rod. 



Stewn6 rudder 
^v / coftrol. 


Fio. 72. Details of the wing warping action in the Wright aerojilane 

body/' no forward cells or empennage, would bring 
K>at most terrible accidents. We had a striking 
[ample of this on May 6, 1909, in the alarming mishap 
hich just failed to cut short the life of the Italian 
ieutenant Caldera, one of Wilbur Wright's pupils, who 
as thrown to the ground by his unmanageable appa- 


ratos capsiring. Also one can inoontrovertibly stata 
that undoubtedly it is ¥^bur Wright himself who ocm- 
■titutes by his presence at the helm the greatest part of 
the yalue of his aeroplane. 

Let us turn to the mechanical installation. Tbt 
engine is a 4-cylinder petrol motor developing 25 hone- 
power. It runs at a speed of 1400 revolutions per 
minute and its weight is from 95 to 100 kilogrammia 
Set a Uttle to tiie right of the Aviator its weight 
balances the former irfien in his seat, which is on tbe 

Propulsion is obtained by means of two screws of the 
same pitch and of the same diameter ; they are wooden 
and their diameter is 2*60 metres. Owing to a oos- 
venient reducing gear they run in oppodte diredaoDi; 
making 400 revolutions per minute; chains transmit 
the power from the motor to the propeller shafta We 
have pointed out the danger of such an arrangement afi 
thiA) which in the case of one of the screws breaking, 
leaves the other revolving, and submits the aeroplane 
to an eccentric movement causing it to capsize. Wilbur 
Wright, since the accident which befell his brother 
and in which the American Lieutenant SeLfiridge was 
killed, has, it appears, happily modified this dangerous 

In order to start the Wright aeroplane a rail and 
pjfion are necessary. The rail upon which runs a ^olle^ 
carriage supporting the aeroplane is 70 feet (21 metres) 
long ; it is laid on the ground and fiices the wind The 
rail b connected with the ** pylon,'' a kind of pyramid 
framework, to the top of which is hoisted a weight of 
800 kikgrammee held in position by a trigger. In 


{ailing this weight releases a cord, which through an 
arrangement of pulleys hauls the aeroplane along the 
rail with increasing speed, since the velocity of a falling 
body is proportionate to the extent of its drop, which 
explains the uniformly accelerated movement. 

This means of launching is ingenious, but it deprives 
the American system of much of its practical value, 
relegating it chiefly to the category of appliances for 
research and experiments. It is an ingenious, an excel- 
lent, demonstration apparatus for mechanical investiga- 
tion, but so long as the Brothers Wright refuse to make 
avail of this launching " rail," so long as they do not 
openly accept the conditions that prevail among all 
French aeroplanes, that is to say, start unaided and by 
their own means, they will hold an inferior position, and 
their machines will lack the features of ** practical " 
utility. It is said that why they do not do so is 
because they do not wish it; such is to be regretted. 
It is true that twice they set out without the aid of 
the £sJling weights, but they were " sped " along their 
rail by men who could push the aeroplane rapidly. And 
then, it is not so much the weight, it is the rail, because 
it decreases to an enormous extent the friction at the 
start We see this every day in the goods stations; 
along rails a horse draws a heavily laden waggon, 
whereas upon the road the same animal could not even 
pidl the waggon empty. 

The Wright apparatus moreover is rather dangerous 
because stabilisation, as much when travelling directly 
ahead as when turning, must always be secured by the 
aid of the aviator, whereas in aeroplanes of French 
construction, especially in the excellent monoplanes, it 


ia only UUkSTfii ^aibiiit;]^ witii which the a^iflCar '» 
(semeii) longitudmal ^aifailiiz^ being eamncsfiL by moHB rf 
the - emparmnKa • ^1« (»a ana axpiaia tia cfii^ 
Chat die ijnericui a^vdatac hw axpffiisiaBd bt izimif 
hie papila ? Hi* haft tawj^ nrnft hnw tn mampnktt kii 
''^ hird " It ie true ;; but this- uuteoixtiim warn cnimiiHnMwi 
a4> nhe AarM^oura camp ducmg the mmitn of AngaBC 19M, 
tasf^ (Hjer seven manthA, and. it wna nan ontil l£»eh 18, 
Iid01>r d^£^ tihe 4E^nr»wnmui a^ittibir £br the Ixcst tmtt (kni 
to perniit hie pupile tie maoagsar their appacalms thea* 
sei^ea ;. ftod e^nsa the mfflatamoy wiidi which: cfe b a* 
aoonesfi that the po^pile hrnrn^ aik hu^ fficpwiL '^akae' 
Acyoid aiadBee ta Aow the ^ffiienilgr of the tariL Oaths 
eMrtnoj the Fffaocbi aaiap&iaaa ace- aa^ sbahlie^ tiiat taut- 
qnentlj four oc fiiRir [ijimiiihh wiffimfr to randor aa aiiittf 
Qa|>at>le of opera(aa^ tlboa with aai&tjr ffiarikBiwa withtia 
Antcin^te aeroplaibe ftr iaotHaea). 

Ne^erthefeaa the Brothers Wr^ht are enfeitled to 
'y^^r^^ii/^lftrarxe praise- They have perfi^cted oce important 
fpffiht in avuit'ori, that of Iat«ai equEibrixim by the 
if#ir^;'iA ?tr'>^'iti':L. of the warping of the wings, and they 
h;kv^« ;{iverj a striking example of perseTerance, for they 
htjiit ^;very pcirt themselves, including their motor. 
Moreover, by their enthnsiasm they have shown the 
true fj^th which must be followed by aspiring aviators; 
f,}ifiy HfiT^e^l their " flying apprenticeship ' in practising, 
fil f}tHt, fttraight flight, by numerous " glides " carried 
ofit with aeroplanes without a motor. Thanks to these 
i(hflnH they were able to discover, one by one, the neces- 
Hfiry firrangements to obtain the best sustentation, the 
minimum resistance. 

Hut, after all, in this they were preceded in America 


by Chanute, io Germany by Otto Lilienthal. In France 
Louis Bl^riot found a brilliant solution which gives the 
lateral equilibrium as surely as warping of the wings — 
the use of '* ailerons " or ** winglets." 

To sum up, the Wright aeroplane, owing to its 
simplification of the arrangements, has been able to 
accompUsh some magnificent '' records " in height and 
speed. Through not having to carry with him some 60 
or 80 kilogrammes more weight, represented by the run- 
ning-chassis of the French aeroplanes, freed from the great 
effort necessary to start, and consequently the increased 
weight of the motor, he has been able to use an ordinary 
automobile engine, possessing greater reliability, and as 
a result better able to secure the records for altitude 
and duration. But he has not yet carried out a single 
real ** voyage " because handicapped by the necessity of 
his launching rail he is compelled to return to his pylon to 
re-start ; if he comes to earth en route he cannot rise again. 

This is where Bl^riot triumphs, for on October 31, 
1908, he accomplished the first aerial voyage in what 
may be described as a closed circle from Toury to 
Artenay and back, descending twice during the journey 
and re-starting under his ovm power ^ passing over roads, 
villages, and wooda Such is an ''aerial tour" in the 
fullest sense of the word, and that date, October 31, 
1908, constitutes in our opinion the historical date in 


M. Maurice Farman, the brother of the celebrated 
^'ehampion of the air," had an aeroplane built at the 


llallet workshoiNi which was ezhibitod at the Aero- 
naatioal Salon in Deoember 1908. 

This apparatus^ yery well oonoeivad, is a ** hiphoa" 
Like the Wright appaiatna^ it admits of waiping oftiie 
wings ; bat meanwhile by means of a sfaliilMlin||i tul, 
it possesses the automatic longitiidiiial stabOhj qf tis 
French apparatus (Fig. 78). 

The two similar, and superimposed sumw r tiu g phooi 
spaced Tertusally 1*50 mefcies ^fmr^ aie redk/Stj 
strengthened by 8 pairs of ashwood ttpaJjghls L Those 
supporting planes haye a qsreadof lOmsAna by S 
breadth. Their individual supecficieB 
20 square metres, and the aggregate 
40 square metres. 

These planes are buih up of ]i|^ and ngti. stajs 
upon^whicfa is stretched, on both sides^ a vamisbed 
cotton fiibric weighing only 85 grammes per square 

The '' wings '^ are mounted upon a spindle-shaped 
" body " of rectangular section, in which are placed 
respectively the pilot's seat, the motor, and the man- 
ieuvring and steering controls. The motor and screw 
are placed behind the aviator; the wheel controUiiig 
the elevating and steering rudders as well as the lever 
jl>r uxifrpirig the ¥ring8 are set in firont of him. 

The '' stabilisatiQg tail " is a '* rear cell " connected to 
the planes forming the '* front cell'' by four long meoh 
bers cross-braced and stiffened by tightly stretdied sted 
wire. The rear cell has a spread of 3 metres, by 2 metres 
breadth, which in view of the foct that it is composed of 
two planes spaced 1 *50 metres apart, gives a total sur- 
of 12 square metres. The curvature of these two 




£levatin| planes. 

/'Skeering wheel. 
Aviators seat. 




cellular box 

surfaces is calculated in such a way that they are slightly 
** supporters " as well as being stabilisators. 

The elevating rudder is at the front. It is a unique 
type, comprising a plane of 4*90 metres spread, by 90 
centimetres wide. It 
is divided into two 
panels, on either side, 
at the extremity of 
the body of the 
machine. With re- 
gard to the steering 
rudder this is formed 
of a vertical plane, 
moving between the 
two horizontal sur- 
faces of the rear cell. 

The engine has 
been specially de- 
signed for aeronau- 
tical purposes by 
Renault Brothers, 
the well-known 
motor-car manu&c- 

turers. This motor Fio. 73. Maurice Farman'8 aeroplane 

comprises 8 cylinders in two series of four, working upon 
a common shaft : the cylinders, in pairs, are arranged 
in the form of a V, the shaft being at the apex of the 
angle. The cylinders are air-cooled. All complete, the 
motor weighs 178 kilogrammes, and has developed, under 
dynamometer tests, 58 horse-power, which gives a weight 
of 3 * 1 00 kilogrammes per horse-po w^r. A special reducing 
gear driven from the motor shaft reduces the engine 

/ plane* 



speed from 1600 reyolutiioDS to 800 revolutions per 
minute at the serew prc^Mller. 

The screw is of wood* It was built by IL GhauvikOi 
who designed the remarkable propeller of the jBayartt- 
CUment. It is of the type whioh its diatingniBhad 
designer calls ** integral screw,'' measures 2*50 metm 
in diameter, with a pitch of 2*50 metres. It is placed 
immediately astern of the two carrying surfiioes, the 
exterior edge of which is slightly indented to aflford firae 
passage for the revolution of the two blades. 

The whole apparatus is carried upon a runninff-dkoim 
which serves for launching and landing. It is foiu>- 
wheeled, the two under the front cell being of 70 centi- 
metres diameter each, and the two under the rear osDi 
little smaller. As the figure shows, the articulated fixb 
upon which these wheels are mounted are fitted inth 
absorption springs to allow descent without injury to 
the aeroplane. 

Fitted with the Renault motor and carrying the 
aviator weighing 80 kilogrammes, the apparatus has a 
total weight of 528 kilogrammes. At Buc it made 
some very successful attempts at flight which served to 
demonstrate the actual possibilities of the machina 

It will be remarked that the cells are not divided 
into compartments. The body of the aeroplane is the 
only surface opposed to lateral drift and giving a fulcrum 
for turning. M. Maurice Farman, however, will box his 
front cell should practice demonstrate the advisability of 
such an arrangement. 

In closing this description of biplane aeroplanes we 
will mention the apparatus which M« Louis Breguet, 
the eminent mechanician and one of the inventors of 


the Breguet-Richet " gyroplane," of which we will speak 
later, built and exhibited at the Olympia Show in 

Breaking away from the general lines followed by the 
Parisian designers, M. Breguet built his machine entirely 
of thin tubular steel of large diameter. The supporting 
wings have 12 metres spread, and are furnished with a 
special differential warping evolved by the inventor. 
This warping assists the wmgs in turning, and can also 
aerve for lateral balancing as well as acting as an ele- 
vating rudder. 

The motor built by the automobile house of Gobron- 
Brilli^ is of 60 horse-power. It drives a two-bladed 
screw 2*50 metres in diameter, the total weight of which 
is only 6 kilogrammes, and which in starting gives a 
propulsive effort of 250 kilogrammes. It will be able 
to attain a speed of 90 kilometres per hour. 

An outstanding feature of this apparatus is the possi- 
bility oi folding the wings by the most simple mechanism. 
In this manner the bulk of the aeroplane, when it is not 
in aerial service, is no more than that of a vehicle having 
the same wheel-base as the supporting wheels of the 
aeroplane. The whole is carried upon a three-wheeled 
running chassis fitted with springs. 

This notable aeroplane is calculated to lift two pas- 
sengers and a ^'useful weight" in the form of fuel and 
oil to the extent of 80 kilogrammes. It is therefore an 
apparatus possessing real features of practical utility. 

mscsiPiHni €» Bomm AntoriMANSs 

hmsa a ^riudi ttil 

Iwd it oaitiitedl 1^ €i^ 
iodattd fif tipo^ M ii 
The MffinJinr €f 
fiuDOUs; ifc k an hiihiriMl ■iwipliiiOji aaoa even At 

Vjn gllA natioii denrad that it should be proeot ved at tbe 

South KeDsingtoQ Museam. In fiu^ it has enaUed tiie 
iUnstrioas aviator to aooomplish Uiat doaUe feat (the 
glory of which no one can even attempt to rob him) ; in 
the first place he completed the first *' aerial journey " in a 
closed circle with intermediate descents^and subsequent^, 
on July 25, 1909, he accomplished that performance which 
created admiration throughout the whole world ; achieT- 
ing in a single flight the passage of the Channel between 
Calais and Dover. Moreover, Louis Bl^riot is entitled to 
a dual distinction ; not only did he evolve his aeroplane, 
but he constructed and experimented with it himself; 
all the arrangements are his ovm work, and we wiU show 
how ingenious, simple, and effective they are. 



The Bl^riot aeroplane in its general lines recalls a huge 
bird (Fig. 74). The supporting surface, set out in a single 
plane, is divided into two wings, one on either side, and it 
is between these that the aviator takes his seat. The 
wings have at their tips small movable " ailerons," iving- 
letSy which serve to right the machine when it dips. The 
spread, body and small wings included, is only 9 metres, 
and the supporting sur&ce has a total superficies of 26 
square metres, the rear comers of the wings being 
slightly rounded. 

The wings are made of stiff parchment, and they are 
mounted upon a framework built of mahogany and 
poplar. The shape of the wings varies as they extend 
firom the body, but they always present a concave surface 
turned towards the earth. The planes cut the air at an 
angle of 8 degrees. At their outer extremities are the 
Btabilisating " ailerons " turning upon an horizontal axis, 
and their movement is controlled by the aviator by 
means of a device which we will describe presently. 

The wing frames are connected to the aeroplane '' body." 
The latter comprises a long spindle forming a *' strength- 
ened beam" with the front section rectangular, and 
triangular at the stem. The longitudinal members are 
cross-braced by ashwood struts, the whole being further 
strengthened by tightly stretched steel wire. The lattice 
structure thus obtained is of extraordinary lightness and 

At the stem of this slender body is placed the 
stabilisating ^^ empennage." This is rigid, and the 
length of the leverage at the end of which it works is a 
guarantee of its efficiency. The elevating governor is 
similarly carried at the rear extremity of the body. It 


may be pointed cmt tliat^ in additioii to ikoB pcineipl 
elevating rudder, the ayiator ean use mlso the tvo 
''aiJerona" attached to the ertremitieB of the twowiiigii 
turned one upwards Uie other downwards, they reBtol 
the apparatus in case of lateral inclination ; moved boA 
in the same directicm they give ascent or descent aal 
act in the same manner as the elevating roddet 
Accordingly one in ascending or descending in a stnig^ 
line can operate these two mechanisms in such a manner 
that their actions are combined. 

Lastly at the extreme rear end of die body is tin 
steering rudder^ a rigid plane turning aboot a vartieil 
axis. The pilot takes his seat in a space provided a ; 
the body between the two wings, having in front of his 
the novel lever by means of which the whole of tb 
various movements of control are actuated. 

This unique manoBuvring device of the Bl^ot sao- 
plane is one of rare ingenuity and simplicity. It is a 
lever and drum which we will now describe in detail 

No one will deny the importance of maintaining surely 
and easily the direction of an aviating apparatus. The 
exti-eme mobility of the aeroplane in the atmosphere 
demands that the apparatus should absolutely answer 
to its controlling mechanism, because therein depends 
not only the regulai*ity of the aerial route followed, but 
also the security, even the life, of the aviator. 

We have seen, d propos of the Wright aeroplane, the 
inconvenience of a multiple lever system, which is so 
complicated and the management of which requires such 
prolonged practice, for each lever movement performs a 
definite operation. 

M. Bl^riot thought that directly the aeroplane beocxnes 


a moving plane in space the moet simple device for main- 
taining a direct line would be one where a centrally 
placed connecting-rod, answering a decided action by 
the aeronaut would be that in which the actuation 
of one plane was communicated to the other, so 

Fio. 71. L. BIMot's monoplane 

that they moved together. This is the only example 
yet perfected for controlling the one moving plane by 

The principle of this system is shown in Fig. 74. 
dose examination will sufSce to show that the aero- 
plane corrects by itself any deviation from stability, 
while travelling in a straight line, whatever inclination 
the apparatus may assutne, irrespective of the number 
and position of the rudders, provided that the latter be 
correctly connected to the controlling plane. Thus is 
effected in one action, and to any desired extent, the 


stability of the aerial yaaMl, and all without dqiri^ 
the aviator of the oontrol of his appaxatns or compeDiDg 
him to maintain that much-desired automatic stabOify 
ipidiich, despite some attendant advantages^ is not free 
from many dangers. 

With the lever and drum command^ thb base of this 
barrel acting as the indicator, and taming in any deaiied 
direction, control is absolutely ''instinctive,'' and the 
aviator cannot possibly make a mistake. Moreover, in 
combining this control with a level such as one uses in 
photography, the pilot can discern immediate^ wbidi 
way he must move his lever to correct the aeroplane and 
thus preserve absolutely perfect stability while travelling. 

Control is eflfeoted by means of a drum connected with 
a control lever with ball-and-socket couplings and ocm- 
sequently able to move in all directions. The dram 
and lever are thus connected together. At the base of 
the drum are attached all the flexible steel wires which 
actiiate the different mechanisms for *' governing" the 
direction of the aeroplane. There are connected to the 
manoeuvring arm two levers for the simultaneous con- 
trol of the motor, which must, indeed, work in concert 
with the movements of the elevating rudder for fear of 
terrible accidents, such as loss of speed in ascending, or 
excessive speed in the descent 

The motor is of 50 horse-power, of the Antoinette, 16- 
cylinder type, with forced petrol feed. The radiator is 
carried in the tapered body of the vessel. The motor 
drives a four-bladed metal screw mounted on a lay 
shaft, has a diameter of 2'10 metres, and 1'40 metres 
'* pitch." This screw is mounted at the front of the 
body ; therefore it " draws " the aeroplane. 


The whole apparatus rests upon a running chassis for 
unching, and to ensure descent without shock. This 
is has two bicycle wheels placed under the front of 
e tapered body. A third auxiliary wheel near the 
^^^m secures balance of the apparatus when it rests 

Tdiperini body 

Fio. 75. The rolling chMsiB of the BU*iiot aeroplane 

vpon the ground. The chassis is built up of a rigid 

^ro88-braced framework of wood and tubes of steel. 

This frame carries the body of the aeroplane (Fig. 75), 

^which reposes in quite a springy manner upon a pair of 

coupled parallel wheels turning about vertical axes. 

The connection between the chassis proper and each of 

the two wheels is by means of a collapsible triangle, 

the apex of which is at the centre of the wheel, a 

trifle below the principal leg, and in which the third 

slides in a vertical tube, and bearing in its movement 

against the head of a spring fixed to the chassis. By 

this arrangement the whole, although not weighing 

more than 35 kilogrammes, can absorb at landing a 

blow of several hundred kilogrammes. Fig. 75 shows 

the side elevation of the tapered carriage with the 

wheeled frame under the front, and also the rear wheel 


tibmiHrgiTvn the ucotuW outiizus g£ rK^ iTi»fti% 1 
I wm\\itn u kaamKtM£lenotIJ[., let nsiw coddiif 1 
aaiNBg. thabtha totuL lunj^ iron end ze od • Q 
mln^- Tfcaw pi w te spread lb 9 matecs; 

wvppin* >'^ I'tittL UfO kilo^unmea : and its initial speei 

)L Umu& ISfimt hMfrboilt i^l slightly dijferent aero- 
[titutttv 'itt)^ '^.. ift vifaiok tfa* annJl wings ((M2ennu) 
i>t' th» HttppurtiiifC sMfAfieBr aKftaiHoidbiiad. in fitvonr (^ 
sim^*- Nwxpuuj;, 'th» aikroofr acet rsfcumd aft felie tm 

ini( mddtt-. TEw Jaxaaeeigmm: of t&ift^HvaiBiiph^an 
inufh IcBB ctuui its ^nBBMMBm^. un|f : IhHrfl^ 6 

reduued to 11 s^iiMn ib^i»; an||^ af «i«tia|( dip, 

PttltMrie ^E.£LP.>. CToiiiHrtibaHiBudikinBftke support- 
. M dbrt of 27 kilo- 




grammes per Bquare metre, but such is the perfection of 
construction that this end is successfully achieved, 
the speed of the apparatus attaining 80 kilometres per 

It was by slightly modifying this aeroplane that 
Monsieur L. BIAriot 
built the admirable 
apparatus which en- 
abled him to cross 
the Channel in 
twenty - seven mi- 
nutes on July 25, 
1909. The following 
is the detailed de- 
scription of this 
historical monoplane 
(Fig. 75b). 

The ailerons are 
suppressed in the 
carrying planes, and 
are replaced by a 
slight warping of 
the wings. These 
ailerons are con- 
fined to the rear on 

OF dov£:r 

Sangatte Baiti^i^ 

FiO. 7So. Map of B1Mot'i:ChuiDe1 flight 

each side of the horizontal empennage ; they thus 
constitute an elevating rudder. 

The wings have a spread of 8 metres ; their 
length in the direction of travel is 1'80 metres 
(exactly 6 feet); total length is 7-20 metres (24 
feet). The superficies of the supporting surface is 
14 square metres. The inclination of the cutting 


tl4 THB OOlKQgaXgr OP 

adge (aog^ of sttMky im 7 Aigitiai TW wenm m tk 
mio prow* 

The molor, haStk hj €hm 
Me; ttdevokpiSO 

Under thceo ffotj di t M i ie tibd MmMttiiiiri 
a wdght of 27 kflognrnmes pw aq[iiam 


We have ^already pointed oiifc tiie tendenef anoBg 
aviAtors to redaoe the fmpet&ckl aiea of the s Mppo t ia g 
•ar&ees, to avdd inoreaeing' their ranrtaaee, wUA 
niiiet balanee the mora and greater aLrwwje THkm 
tendenoy we eee manifteted a eeoond time in net 
of the moat remarkable aeropianea among ihw 
whioh have yet berai bnilt, that of IL Bobert EaDub* 
Pelteriei whioh ita inventor^ bo iro w U ig the tiuei 
initials of hia name, deaoribea nnder the abfarenatin 
" RE.P." 

Among the already important group of French aviators 
M. Esnault-Pelterie occupies quite a distinct positian. 
Though very young, he set out on the " path through 
the air ''as far back as 1903, when the rumour of the 
exploits, mysteriously held in secret, of the Brothers 
Wright roused ambitions in him which led to success- 
became resolved into persevering, continued, and rational 
experiments. The young aviator (who at the time of his 
appearance felt himself to be, nevertheless, one of the 
oldest) sought nothing from anybody. He himself, bj 
his own means, conceived, constructed, and tested his 
aeroplane, which he knew to be a marvel of construction 
at the time from the point of view of appearance and 
solidity. And, moreover, being a practical mechaniciaD, 


he created and made every part of a new type of explo- 
sion motor, absolutely novel because of its compactness, 
exceptional lightness, and at. the same time reliability of 
action. So in the aviating apparatus that he fashioned 
and brought to success everjrthing bears the imprint of 
his personality — the general lines, construction, motor, 
and even the arrangement of the running launching 

The Esnault-Pelterie aeroplane is a monoplane, dis- 
tinguished by its flexible warping wings, and stem 
supporting surface fulfilling the function of the ele- 
vating rudder. It is fitted with a stabilisating em- 
pennage, and its rolling chassis is mounted upon two 
wheels "in tandem,'' which support its weight, the 
tips of each wing carrying a wheel for contact with 
the ground. 

The shape of the body of the aeroplane is fusiform. It 
is built up of steel tubes (bicycle tubes), autogenously 
welded together ; moreover, they form a triangular net- 
work similar to strengthened trelliework, which assures 
complete indeformability of the system, as well as rigidity 
and strength. 

The wings have a total spread of 9*60 metres, and 
their design is in accordance with the results of lengthy 
experiments carried out by the inventor. Their surface 
is 15 '7 5 square metres ; as they support the whole weight 
of the apparatus, which aggregateis 420 kilogrammes, this 
represents a proportion of 26*600 kilogrammes per square 
metre, the same, be it noted, as in the new aeroplane, 
Bleriot XL The wings are of wood, flexible, strong, and 
light. They are made in slips, strengthened lengthwise 
by steel and aluminium. Over these wings is stretched 


the &faric, wliioh is the sni&oe o ffi ged to the renstant 
aetionoftheair. Each of theee iringi is stratdied onder- 
neath by two aeta of rapes coiiTargiiig to a point beoeath 
tiie ohaana, and fay whieh the waxpin^ ia aoocmiplishei 
Eachof theaeaetaof rapea aap p o gi a a.fiwirthaf thewei^t 
of tiie apparatus. They ai9 plainly ahown in the photo- 
graph, Plate XXYIL 

Viewed from abovOi the Eanaolt-Pelterie aeroplane 
strikingly resembles a Inid, with itsfim-dbaped tail formed 
by the spreading of its feathers. The snrfiuse thus shown 
(Hg. 76) has a variable indinatkm at its raar end, thereby 
forming the elevating rudder, under which is placed the 
welt-balanced steering rudder, turning about its vertical 
axis ; it is what is: called in marine praotioe a " compen- 
sated ** nidder, because the axis of rotation paaaes throng 
its centre instead of at one or other of its aides. Under 
the body is a veritable " keel," which aeeuras longitadinal 
stability. The pilot has his seat towards the front of the 
body of the aeroplane, and the screw is at the extreme 
prow; therefore it *' draws'' the machine through 
the air. The pilot, owing to the tapering of the 
prow, has a clear view of the ground in front of him 
when the aeroplane is running along preparatory to 

The steering and manoeuvring control are by means of 
levers and pedals. The manipulation of an aeroplane 
comprises two essentially different operations, corre- 
sponding to two widely divergent requirements. There 
is first assurance of stability at starting, and aflerwards 
the maintenance of forward direction. For each of the 
two manoeuvring operations M. Esnault-Pelterie has pro- 
vided a vertical lever. Stability itself also comprises 



3 variants; longitudinal and lateral stability respec- 
ely. The lever which controls stability has two 
vements, one to and fro, the other from left to right. 




Motor Verticals plane. 




Fio. 76. Esnault-Pelterie's monoplane 

r this purpose it is fitted with a universal joint, and is 
, to the left of the aviator. When he moves it from 
b to right, or inversely, it warps the wings through the 
ir sets of under-stretched ropes ; when he moves it from 
nt to back, or vice versa, it actuates the elevating 
Ider, and as a result enables the aviator to recover his 

y -^ * „ ■ ; ' '^"'**'*.S5^ '^'^r'^i^Z'^^. F ^"^^^.s^.^^r^jM.^rrsm- ^ ^ 

« ^ '■'■*« i •* " - "■•< * . ' * . • • 


loDgitodiiial bakiiae» w, if lie m dmktm, to aaoeod or 

13ie Mocmd lever k plaeed in front d the plofe; ooe- 
trolling lateral diree&m, it m moved tnnevetaelj, and 
eommandg the steering rudder* One een aee wbtt 
ingemiity axul rational nmfdmty faaTe acoompmiiri 
the design of these steerio^ deviees ; the aviator mmk 
push the levers in the direetion in wfaidb he vnshes \m 
aeroplane to go ; the movements wfaiob he has^ tiieie- 
fore, to carry oat himself for this purpose are, ao to qpdk^. 
refleziye, and error is impossible. Finally, two peddi, 
allow the aviator to control his motqr, one actof 
npon the gas inlet, the otiiw open tibe propeBflr 
connection. I 

So fiur as the motor is ccmcemed, we have alreaity hsl' 
occaaon to describe it. The Esnralt-Pelterie (B.£P.) 
engine is one of the most ori^poial and one of the best- 
conceived that there is in aviation circles. When this 
excellent engine was completed La Soci^t^ des Ing^nieurs 
Civils awarded their prize to the inventor. It is of 30-35 
horse-power, and its cylinders, numbering five, seven, or 
ten, according to the power, are disposed in two "semi- 
stars," but in such a manner as to be all above the hori- 
zontal diameter of the figure. In this manner lubrication is 
perfect. The valves are of the sliding type, and, according 
to their position, permit admission and exhaust ; there 
is one to each cylinder, and they are operated by a single 
cam. There is no water-circulation, the cylinders being 
fitted with fins, and at a speed of 45 kilometres per hour 
cooling is very perfect. The motor, of 30-35 horse-pow^, 
weighs 68 kilogrammes complete. An oil reservoir 
of 6 litres and a fuel tank of 40 litres suffice for two 


hours' continuous flight under the propulsion of a four- 
bladed screw 2 metres in diameter, mounted direct on 
the motor shaft. 

In completing our description of this remarkable aero- 
plane, it is only necessary to say a word about the rolling 
chassis used for launching and landing. The body of the 
apparatus is carried upon a pair of wheels arranged in 
" tandem " ; under these circumstances it falls to the left 
or right ; but the tip of each wing being fitted with a 
special wheel, permits the apparatus to run along the 
ground without bringing the wings into contact with the 
latter. Immediately the apparatus is launched, the 
aviator, by the aid of the warping lever, lifts the wing 
which is trailing, and the equilibrium of the machine is 
established. The j&ont carrpng- wheel is mounted upon 
an ''oil-pneumatic brake," assisted by a spiral spring. 
Under ordinary circumstances the weight of the apparatus 
is flexibly supported upon this spring. Vibrations caused 
by the unevenness of the ground are absorbed by an air 
cylinder, in which moves an air-compression piston. 
Finally, the shock in landing is taken up by an oil brake, 
in which this liquid, compressed by the blow, is forced 
through a very small orifice : this brake, which weighs 
only 6 kilogrammes, can absorb 350 kilogrammes. One 
can see, therefore, that it is very efficient for the landing 
of the aeroplane. 


Among aeroplanes of the monoplane type, the An- 
toinette deserves particular mention. Every one knows 
that the motors of this make have already furnished 
aviation with an engine powerful combined with light- 


■■* cftnried to mdb a degne tfcsfc a lOO-faonB-pover 
■vtor en be tfiiiMirtHi by «■ ■11114)1 h«& TW. 
boiUm nf Itirar nynw W^ahp ■■ifcilalim thseoB- 
■IraetUD of aeroplBDe*. and in tbea- ckiee fixed opCD 

Tbcrjr aUrted boOdtiig the acvoiilNM Gawttmiimit- 
Hengin, which aenred thcB as a BHana of 
and reaearch, and, bj improri 
tbey at last prodaoed a Btnking ^^le, wluefa ia known m 

Tbfiae constmctorB, like bo many other aviators <^ 
to-day, preferred the moaopUine because of its extreme 
Mimplicity, facility of constructioD, and greater efficiency, 
recjiiiriDg leaa power for progrearaon through the air onder 
the same conditions of weight and epeed. 

One of the most remarkable features of the Antoin^te 
■eroplaneH is the design and build of their supporting 
mirTarj-H. Tln_^se, divided into two elements consti- 
tuting wings in every sense of the word, have the 
form of trapeziums, %he larger base being contiguous 
to the body of the machine. When seen &om the 
front the apparatus has the appeamnce of a very 
open V. 

The section of these wings is of such form as to secure 
the maximum of " power of penetration." Their surfaces 
are covered on both sides, and the fabric is mounted upon 
u framework which is certainly a marvellous piece of 
work from the triple standpoint of rigidity, solidity, and 
lightness. This framework is composed of an assemblage 
of longitudinal and transversal ribs, intersecting one 
another so as to form a series of triangles, the whole 
being consolidated in a rigid manner by riveted aluminium 


" gussets." The wing surface is 25 square metres, and 
yet their weight 'ib scarcely 30 kilogranunes. One can 
thus see that the total supporting surface is 50 square 
inches. The extreme spread is 12*80 metres. It is 
very interesting to note that the builders have designed 
their framing upon the lines and methods of the con- 
structors of metallic bridges and the Eiffel Tower, 
which consists of subjecting every part to tension and 

The body is triangular in section ; it is a long girder, 
ending at the front in a pyramid, prismatic at the wings, 
and then tapering towards the tail of the apparatus. It 
is likewise built upon the principle of metal bridges ; at 
the same time it is light and rigid. Body and wings 
are covered with fabric, carefully stretched and given 
several coats of vamiBh : this imparts to the surfaces 
moving through the air a remarkable smoothness, re- 
ducing to the minimum the friction of the molecules of 
air coming into contact with the force which displaces 

The constructors of the Antoinette aeroplane have 
abandoned warping the wings for the following reason. 
With Louis Bl^riot, though in a slightly different form, 
they have adopted the ailerons fitted to the tips of the 
carrying surfaces. These ailerons, which one may see 
very distinctly in the photograph of this aeroplane, are 
connected to the back edge of the wings, and when at rest 
form a prolongation thereof. - They are connected with 
the latter by an articulated system which lowers one 
while it raises the other. This produces the same effect 
as warping, but with greater power and without the in- 
xx>nvenient danger of fatiguing the wing framework by 

Coatrol is dBectod bf 
three wheels. One may 
not re&un from think- 
ing that snch is too 
much for an aviabv 
wbohasonly (lOD haods. 

rit.n. The-AntoinetW-mooophoe j^^ ^^ ^j,^,^ Control- 

ling Kteering and the ailerons respectively, are close to- 
gether, it is true, so that the hand can pass easily from one 
to the other. For my part, I think that it would be po-haps 
wiser to have recourse to a control arrangement of the 
ilMriot aeroplane type. That is the only criticism which 
I can offer of this apparatus, the conception and the con- 
Htruction of which from all points are remarkable. In 
(iddition, two bandies control the ignition and the inlet 

■ ■LATE .\SVtlA 


throttle of the motor, and there is a foot-brake to stop 
the engine. 

The whole apparatus is carried upon a supporting 
chassis composed of a '' roller skate " placed under the 
firont of the body, two '' shores/' one at the right and the 
other at the left centre of each wing, and a " butt-end " 
under the tail The ** shores " and '* butt-end " are set in 
the direction of travel. The " roller-skate," comprising 
a bicycle wheel at the back and a roller at the fix)nt, 
owing to an ingenious and solid suspension spiral spring, 
admits of absorbing to the maximum the severe shocks 
which are produced at the moment of landing. The skate- 
wheel, almost under the centre of gravity of the appa- 
ratus, is so placed that the strain upon the tail is reduced 
to the minimum. With regard to the " shores," not only 
do they preserve the wings from all rough contact with 
the ground, but they serve as an anchoring point for 
the upper consolidating ropework. Moreover, a vertical 
piece serves as a straining support for the cords stretched 
over the upper face of the supporting surface. 

When one wishes to launch the apparatus, one starts 
the motor and connects the propeller : the aeroplane is 
supported on the ground by its skate, shore, and stern 
butt-end. As the speed increases it is the butt-end which 
first leaves the ground ; after some lateral oscillation the 
shores in their turn rise. Released, the apparatus gradu- 
ally balances itself while poised upon its roller-skate, 
until at last it definitely rises. 

The motor is, naturally, an "Antoinette." It has eight 
cylinders disposed in a V, and develops 55 horse-power. 
It is placed towards the front, and drives a two-bladed 
prow propeller of 2*20 metres diameter. This screw is 


of metal ; its shaft is a steel tube with blades of aluminiom 
riveted to the boss, which is flattened out into the shape of 
a fan. Its pitch is 1 '30 metres, and it runs at 1 100 revola- 
tions per minute. One can change the set of the two Uadeni 
and consequently modify the pitch. By means of ex- 
periment one can thus ascertain the most advantageous 
pitch for the best regulation of the track of the aeroplane. 

With regard to the pilot's seat, exceptional precantioos 
have been observed to secure ample accommodation for 
the aviator : the position is well sprung, so as to pre- 
serve him as &r as possible firom all shocks, and at the 
same time allow him the greatest freedom in movement 

Such is the superb monoplane, the construction of whidi 
from all points of view is striking. Perfected by M. Wei- 
feringer, it was taken to the camp as at Ch&lons, and 
there placed in the hands of M. Demanest, who served 
his apprenticeship as pilot. 

After Jive lessons only, the young aviator was able not 
only to ** fly," but to win, on April 8, 1909, the latest 
prize of the Aero Club of France for 250 metres. M. 
Henri Farman, passing through the camp at Ch41ons, 
oflBcially timed the trip, and warmly congratulated the 
new aerial navigator. 

And on June 5, 1909, the Antoinette aeroplane accom- 
plished another performance : M. Latham, scarcely 
familiar with the management of this remarkable aero- 
plane, flew for one hour seven minutes^ darkness only 
stopping him then. The following day, not content with 
having beaten the world s record in a monoplane, he set 
out with a passenger. The day after he performed an 
unprecedented achievement in aerial flight, for, besides 
himself, he cairied two passengei*s, MM. Fournier and 


Santos-Dumont, and demonBtrated once and for all by 
[lis marvellous skiU, the safety and facility of manipula- 
bion, and consequently the absolute superiority, of the 
French aero-monoplanes. 

Finally it was with this aeroplane that Hubert 
Latham was able to cross the Channel, after M. Bl^riot, 
uid to reach within less than a mile of the English 

This feat, so rapid, this safety, so promptly acquired, 
demonstrates better than words how great is the security 
of the French aeroplanes, and how much easier they are 
to control than the apparatus which, like those of the 
Brothers Wright, demand everything from the aviator. 
And this rapid initiation is not the only one ; upon the 
BlSriot^ EsnatUt'Pdterie^ Voisin, and Antoinette aero- 
planes flying can be learned in a few lessons. This 
exemption from a long, laborious, and perilous ap- 
prenticeship is therefore quite a triumph for French 


Among the apostles of aviation is a man who, one can 
safely say, has devoted his life to the advance of ^^ the good 
fight " in favour of transport by machines heavier than 
the air ; not only has he contributed some remarkable 
works upon this subject, but he built an aeroplane model, 
which was tested at the Chalais-Meudon riding-school 
in 1879 before a number of officers ; this model was 
{nropelled by a screw driven by a compressed-air motor. 
Ab a result of his efibrts, Tatin deserves to be placed 


beside Penaud, Langley, Bichet, Marey, and the oth^ 
notables of the *' Pleiade " of initiators. 

Some time ago, Victor Tatin conceived a type of 
monoplane in which he sought to emulate the bird hj a 
'' soaring plane." M. Clement, the automobile eogine^, 
of whom we have already spoken in connection with our 
description of the magnificent dirigible in the first part 
of this book, enabled the inventor to carry out his idea, 
and the TcUin aeroplane which, like the dirigiUet ^ ^ 
known as the Bayard-CUment^ is now building at the 
workshops of M. Ghauvi&re, the aocompliahed and skiDed 
designer of aerial screws. It is impossible to pas in 
silence this aeroplane, of which much has been said prior 
to its appearance, and on the subject of which ]£ Tatin 
has written a very excellent book entitled MemefUs 

Seeking to imitate the soaring bird, the Tatin wsro- 
plane is perforcedly a monoplane. The inventor has 
pointed out that in the soaring plane the tips of the 
bird's wings are bent slightly upwards. He has conse- 
quently imparted this form to the transverse profile of 
his wings, which, instead of being separated from one 
unother, constitute by their combination, a continuous 
surface which projects horizontally, forming an elongated 
ellipse. The surface of the rear empennage takes this 
form also ; the spread is 12*50 metres. 

The general appearance of the Tatin aeroplane is 
totally different from any we have yet seen. It is dis- 
till j^uisheil hy the elimination of all parts capable of 
oflering resistance to movement and not acting as sus- 
taining surfiices, recalling on the whole the general 
outline of the bird known as the martin. The wings are 



curved, their convexity being turned towards the 
ground ; the supporting surface has a span of 25 square 
metres. The stabilisating tail is 4*40 metres from the 
wings, has the same curved form as the latter, and its 
surface is 7 square metres. 

The body of the apparatus is rectangular in section, 
the sides being 90 centimetres. It is 6*50 metres 
long ; it is really a " strengthened gu-der " carrying the 
motor, the aviator, and tanks for petrol and oil. As it 
is imperative that these resistance surfaces should be 
held taut by shrouds, there are two thin vertical members 
and eight steel wire shrouds, so arranged that they meet 
above the surface of the tail for this purpose. 

The front of the aeroplane is connected to the stern 
by two wooden members spaced a sufficient distance 
apart to permit of the propeller revolving between 
them. The latter is of wood ; placed at the stem 
of the body it is of 2*40 metres diameter, and has a 
pitch of 2*50 metres ; it revolves at 700 revolutions 
through a reducing gear mounted on the motor shaft. 
It is built up of thin superimposed sheets let* into the 
framing and assembled in such a manner that the 
true form of the structure is preserved. The whole 
is covered with varnished Japanese silk. 

The motor, specially constructed at M. Clement's ate- 
liers, after the designs of M. Clerget, can develop 60 hoi*se- 
power, which can at will be reduced to 30 horse-power. It 
is placed behind the aviator, and has radiating cylinders. 

The stabilisating tail serves at the same time as the 
elevating rudder. For this purpose it can be slightly 
inclined upwards or downwards. A vertical rudder fixed 
to the tail secures lateral steering. 

Front elevation- 
Rudder Tail 


When the apparatus is in full flight it does not require 
more than 25 horse-power, and will fly under such effort 
at 72 kilometres per hour. By using the whole of the 
available motor power this speed will be possible (f 
increase : the aggregate horse-power is a little more 
than twice 25, which 
will multiply the fore- 
going speed by VZ 
thus giving a speed I 
of 90 kilometres per 1 
hour. This aeroplane 
will thus be one of 
the fleetest. Well 
thought out, as a 
result of prolonged 
study by its author, 
marvellously cod- 
structed by the en- 
gineer, Chauvifere, it 
is now completed, 
and its tests are 
keenly anticipated. 
Another very io- 

WlQ. 78. V. Ttttin'i DtonopUne •■ 

opIuM^ the 

teresting aeroplane is that which has been built and 
successfully tested by M. yend6ine. Here we find 
again that tendency, of which we have already spoken 
in Bleriot XL and the Esnavlt-PeUerie aeroplanes, 
which consists in reducing the spread by the decrease 
of the superficies of the wiugs, and the augmentatjon 
of speed. This tendency we shall find more accen- 
tuated still in Santos Dumont's very ingenious little 
flying apparatus- 


The Venddme aeroplane is fitted with two separate 
wings, symmetrically placed on either side of a fusiform 
body, having a quadrangular section. The membrane of 
these wings is of very light, tightly stretched, unvar- 
nished fabric. The wings are disposed upon new and 
quite qriginal lines. M. Venddme has sought to combine 
the ^' ailerons " with the warping action, thereby making 
use of both these systems. To this end each wing can 
be pivoted upon itself, independently of the other ^ by one 
of the control levers. This is equivalent to warping the 
whole of the supporting surface and ensures the main- 
tenance of transversal stability. In manoeuvring the 
two levers simultaneously one can change the angle of 
incidence of the wings and so ascend or descend. More- 
over the two wings present, as in the Antoinette aero- 
plane, the form of a very open V. A stern tail obtains 
longitudinal stability of the apparatus and acts likewise 
as the elevating rudder. 

There is no steering rudder ; turning even in a very 
short radius is obtained by means of the extreme ailerons 
placed above each wing. When at rest the ** ailerons " 
lie upon the supporting surface ; the pilot, by the aid of 
pedals, raises them when he so desires, producing a 
dissymmetrical resistance to the air, thereby securing his 
horizontal line of travel. The motor is of 50 horse-power ; 
it drives direct a hoUow screw of hickory wood veneer, 
mounted on canvas, of 2 '43 metres diameter, and of 
which the weight is only two kilogrammes. The whole 
apparatus rests upon a three-wheeled running chassis 
fitted with absorption springs. 

The whole apparatus is 12 metres long, and has a 
spread of 9 metres only. The supporting surface is 24 


iq^H* aataiV Md «fc» talil w^ll^ dns not oeaed 31V 

iirii I ii I II iirtiii It I iT irrr'Ti i 

llMlw It ^lll l. Illll n i'iiMi.mTI llllt ■ lllllliri I 1 

139 liliiyiwMiM m total w^gK nib » tfaii toaik- 
dbia lagJM. vU tAmA wA St. Cjt, cwdy m A^ tihe 

TfcM ■ iJMtMliil mil Ae &et that one «a gy wittiort 


iribeeB, of we^itjand c 

mmdunet. Before imtg, UmdIes to tlw explodon notar, 
the arti6esal liird of Uam weigfat and Tolmiie wiU be dik 
to go an y wh er e. A little mora prograa and ervery flos 

will fly. 


We see from tlie forgoing tliat wb are oonfrooted fay 
two schools of aviating apparatos : the American sdwol, 
represented by the Brothers Wright, which demands 
everything of the aviator, and the French acbod, Yoisin, 
Bl^riot, Esnault-Pelterie, Antoinette, which requires, en 
the other hand, the minimum from the pilot. 

Which of the two is correct ? 

The best way to reply to this qaeetien is to quote the 
words of Paul Painlev^, Sorbonne Professor, and member 
of the Acad^mie des Sciences. M. Painlev^ is not one 
of those abstract mathematicians who confines himself to 
differential symbols or the study of elliptic action. He 
has probed into aviation practice, has flown in turn witii 


Wright at AuvoarB, and with Farman at the Gh&lons 
camp, and this is how, in a snhsequent article, he ex- 
pressed himself upon the subject : 

'* Aviation is the most burning mechanical problem 
appealing to mankind to-day. Its soltUian is (ichieved. 
To-morrow it will be commercial ; in a few years it will 
commence to transform the world. This solution one can 
now indicate upon broad lines. 

** Two schools are represented : the French and the 
American, or if one so prefers — ^for it is confined to the 
two constructors who have effected the most impressive 
results — the Yoisin and the Wright systems respectively.^ 

** In the first place an aeroplane to be able to support 
itself in the air must travel quickly, and at such a speed 
that the resistance of the air, increasing with the speed, 
prevents it from falling, whence the necessity of a motor, 
powerful, light, and regular in action at one and the same 
time. The more swiftly an aeroplane travels the more 
stable and capable will the apparatus be of combating 
the caprices of the wind. The perfection of an ideal motor 
is no more than a question of months. 

*' Then it is imperative (and this is the gravest di£Eiculty) 
that the apparatus neither dips forwards nor backwards, 
neither to the right nor lefl ; it must not even deviate 
from its direction of travel. In a word, the aeroplane 
must not pitch or roll, or swing round suddenly, or else 
the pilot must be able to restore such unbalancing move- 
ments as soon as they develop. 

^ At the time the eminent mathematician wrote theee words (2^ 
J/irttn, October 28, 1908) M. Bl^riot had not made his "historical 
journey " in a doeed circle by monoplane, and Latham had not accom- 
plished his well-known brilliant triumphs on his *' Antoinette " 


"Here are the meuuof obtainii^ tliia ■tahility, whiA 

are different in the two aohooli. 

" Wright haa aonght ahove all mwapGekly and li^liw. 
bat the equil&frium of Aw appamtiu w emiirjg m Ae 
hand$of the ptioL Three diatinot movanoBta tmM 
the three poanble perturbatu»ia ; waxfiag of .A* wiiy 
parUoularly oounCeraota ndling. 

" In partitioning the two winga liks the ooBa of a kita 
In the form of a cigar-box, Voiain, on the contrary, eecont 
lateral stalnlity. In turning tfieir apparatut awww» 
tUelf to the mott eonvenwnf ttneHjialion, Two opentiooi 
instead of three an all that is necessary to control Un 
machine : that of the ateering rudder, and that <^ th& 
elevating rudder. Y^ tkia last corUrol is now verf 
timpUJied 6y the addition of a long taSt wkidt eppom 

" Laatly, the utaliaation of the motiTe power throogh 
the large alowly-tnming acrewa of the Wright, or IJm 
shorter and higher speed of the Yoisin, appear com- 

" The Voisin apparatus is decidedly heavier than the 
Wright (650 kilogrammes instead of about 500), due in 
the first instance to the tail, and secondly to the running 
chassis (80 to 100 kilogrammes) necessary to enable the 
apparatus to raise itself under its own effort. 

" These differences, well specified here, are the result 
obtained by the two apparatusee. Wright lu^da the 
record for distance by himself and with a passenger. He 
htu tiever yet raised himadf by his own effort. He will 
be aUe to do so though when he so deeiree, but wOl it be 
^pUhMU increasing weight ? " 

The Voiun apparatus, piloted by Fannan, holds the 



record for speed : 70 kilometres per hour at least ; 
but it must be pointed out that it is always self- 
lifting by means of its running chassis, weighing 80 

Before my own eyes Farman flew in a violent wind 
(October 28, 1908) above the camp at Chd^lons ; he made 
the first long distance flight that had ever been attempted 
in an aeroplane ; he flew not only in public, but before 
some officers who attempted to overtake him at the gallop. 
He repeatedly described his usual circuit at great alti- 
tude, frequently exceeding 40 metres. Lastly, notwith- 
standing the weight of his running chassis, it lifted it- 
self and me by its own effort^ and traversed a distance 
of 1600 metres, and the apparatus completed a turn 
showing as perfect a stability as if the pilot were 

" A magnificent day's work for French genius ! " wrote 
a young officer who was overcome by enthusiasm at these 

It would be useless to add a line of comment to this 
criticism by one of our most learned mathematicians, a 
criticism formulated on October 28, 1908 ; and two days 
later Farman and Bl^riot substantiated his statements 
by completing, on the 30th and 31st of the same month, 
the two "first aerial voyages" from town to town. 
That is a distinction of which none can ever attempt 
to deprive them; they were the two first "tourists of 
the air.'' 

One can by means of so exact a comparison intimately 
grasp the fundamental difference between these two 
" schools " of aviation. We see that the American school 
demands everything of the aviator, longitudinal^ as well 


as lateral, stability, whilst the French school assures Ute 
longitudinal stability by means of an empennage and a 
long leverage arm, which is an important point The two 
schools may best be likened to those two machines, the 
monocyde and the bicycle respectively : neither has latenl 
equilibrium, and the rider must secure it in the same 
manner upon both, but upon the monocyde he must also 
obtain longitudinal stability, whereas, on the other hand, 
with the bicycle this is inherent, owing to the two sup- 
porting points on the ground 

Consequently while every one can control the bicycle, 
only those expert in balancing will risk themselves upon 
a monocyde. 

Our French aeroplanes : BUriot^ Voisin, Antoinette^ aie 
the bicydes of the air ; every one will be able to use them, 
and the latest exploits of Latham at the ChMons camp 
where, after only a few lessons, he was able to remain in 
the air on his Antoinette aeroplane for sixty -seven 
minutes y to lift two passengers, &c-, demonstrate the 
facility and safety of their management. Lastly, it 
was on a Bleriot monoplane and an Antoinette mono- 
plane that the sea was crossed for the first time with 
apparatuses heavier than air^ mounted by Bleriot and 
Latham towards the end of July 1909. On the other 
hand, one knows the long practice, the skill that is 
requisite to use a Wright. Wilbur Wright possesses this 
Hkill to an extreme degree, but it cannot be acquired by 
every one, no more than any one can become a mono- 
cyclist : the serious accidents that have been precipitated 
by the American aeroplane demonstrate this fact in an 
overwhelming degree. 



A word remains to be aaad about aTiatioo i^pantm 
based upon prindples other than these of the aeroplane ; 
there are, first of all, the hdioopfeftras^ or apparatus with 
aostainiog screws. UntO now these aj^Huratas have not 
given decisive resolts ; it is true one sacoeeded in lifting 
fidrly heavy apparatus finom the ground on several occa- 
sions, even with the aviator ; but what is difficult, and 
what is so fiur only promise, is the constant direction of 
the apparatus through the air. The efforts of investi- 
gators have been confined almost exclusively until now 
to sustentation by screws. We have mentioned the 
works of Colonel Benard upon tins subject, and the 
hopes inspired by rather hasty interpretations of the 
formulas which summed up his calculations. To-day a 
few trials of direct sustentation by helixes have been 
realised, and the most important are those of Engineer 
linger (Monaco), M. Paul Comu, and M. Louis Breguet. 
We have already spoken (p. 181) of the firet of these 
apparatuses. Let us now say a few words about the two 
others, which have furnished interesting results. 

We know what the ** slip " of a helix is ; similar to a 
screw, the propeller turns in the air, but the mobility of 
the molecules of the latter causes the apparatus only to 
advance a fraction of its ** pitch." The difference defines 
the slip. 

Until now, in the sustaining screws tried with h^li- 
copt^res, attempts were made to render the slip as small 
as possible, and to do this by decreasing the pitch of the 
screw. This slip, however, cannot be entirely overcome. 


M« Comu therefore, not being able to avoid it, soaght 
to use it for the horizontal propulsion of the aviatin 
apparatus. This is the principle of his apparatus. 

A frame carries a motor, which transmits its power 
to two screws through endless belts, one to the right and 

Sf^hf hand propellor. Left hand propeilor. 

plane propellers. I I plane propellors. 


Fio. 79. Principle of the Ck>rna H61ioopt^re 

the other to the left, and turning in opposite directions 
to annul torsion efforts. These are the '* sustaining " 
screws devised to lift the apparatus into the air. The 
effect of their slip produces back- thrust of the air 
towards the bottom, whereas their useftil effort secures 
the sustentation of the apparatus. This driving back 
of the air is used for horizontal propulsion by means of 
inclined planes placed under the screws ; these inclined 
planes receive the rush of air driven from the top down- 
wards, and their oblique surfaces transform this vertical 
effort into a horizontal component which may displace 
the apparatus in a given direction. By differently in- 
clining two series of these planes placed on both sides 
of the axis, turning and inclination may be obtained. 
Such is the principle of the Comu apparatus. Plate 
XXIX. represents its real construction. The results seem 
encouraging ; the apparatus rose once with its aviator 


>n board ; a second tinie w::h two LLien, the total weight 

^TUfted being 32 S kilo& This sustentation lasted one 

minute. The propulsion, according to the horixontal 

effort exercised upon the oblique planes, was weak : 

only 12 kilcMnetres an hour. It may be seen from the 

^^bregoing that this h^oopt^re is amongst the most 

iterestiog, and such researches must be encouraged, as 

3>fc 18 from this development that the perfect sustaining 

^i«crew will doubtless be eyolyed, and which, perhaps, 

Bome day it will be possiUe to associate with the 


It is necessary to mention specially a very interesting 
aviation apparatus, the gyrcplane of Messrs. Breguet 
and Richet, realising in a happy manner the combination 
of the aeroplane and the hdlicoptdre. This apparatus 
comprises an association of Jixed wings and of revolving 
wings. The photograph enables their arrangement and 
operation to be very clearly understood. 

The total surface of the revolving wings is 1 1 square 
metres each ; the surface of the fixed wings is 50 square 
metres, which, in the event of a vertical descent, pro- 
vides a total area which would form a parachute of 
approximately 72 square metres. The oblique disposi- 
tion of the screw shafts is seen ; the reaction of the air 
upon the fixed surfiuses gives in this manner, as soon 
as the propellers are in motion, a double effort : an 
upholding vertical effort, and a horizontal effort serving 
for forward propulsion. 

With aviator and petrol for one hour, the apparatus 
weighs 600 kilos ; the engine is an " Antoinette " motor 
of 40 horse-power. A warpable equilibrator placed at 
the bow, and lateral small wings, ensure stability, and 




allow the aviator to regain each in the event of acfr 
dental ioclination. A steering mdder is placed at the 
stem of the apparatus bodj, and acts as the verticsl 
WDpennage. The fixed and revolving surfaces are supple, 
and constracted apon very ingenious principles; thtsj 
are covered partly with very thin aluminiuin sheets, anc 
partly with special waterproof and non-bygrometrial 

The apparatos has been successfully tested at Doua^ 
on groond purposely selected as unsuitable for t^ 
launching of ordinary aeroplanes ; the area was beetiwl 
fields. The apparatus rose, however, straight into tbf 
air with the greatest facility. An accident internipteJ' 
the experiments, but the results are most encouraging 
and of a nature to induce the authors of the appanita| 
to persevere in the path they have selected. 

The ormthoptkre has been studied and constructett 
upon rational lines by a Belgian aviator, Mr. Adh. de I' 
Hault. Witboat seeking to " fly " right away, thin 
distinguished oonstnictor first set to the study, working, 
and efficiency of the " flapping " wings, and constructed 
an ingenious apparatus, which, with organs of a ver^ 
elegant mechanical conception, realise the movement 
in the form of the figure 8, according to the curve 
which mathematicians call " lemniscate." Thanks to 
this complex movement, the author hopes to realise the 
double function of the bird's wings, both propelling and 
AiiAtaining. The apparatus of Mr. de la Hault figured 
in the 1908 Brussels Kzhihition, and the mechanical 
part, quite remarkable, was much admired by engineera 
The inventor is now pursuing his researches, and impor- 
tant results will certainly be obtained. 


There remains but to point out an American omithop- 
tire with flapping wings, provided with Venetian blind 
Uades, which close when descending, to rest upon the 
air, and open in ascent. We have no data regarding 
ihe practical results of this apparatus. 

Finally, to conclude this history of the principal avia- 
tion apparatus as constructed up to now, we may say 
with confidence that the aeroplane has alone, so far, 
furnished really practical results, and that in its various 
forms it has shown an absolute superiority over the two 
other aviation systems. This justifies the enthusiasm it 
has provoked and which its continuous development is 
maintaining. What it is necesssry to do is to ascertain 
how either supporting screws or propelling surfaces 
oould be added to it. One can therefore see, with the 
aeroplane in its present form so ftill of promise, that 
aviation, the '* heavier than air " science, is far from 
having said its final word ; it has barely said its first. 




Lsr vm noir, knowing the eonditioiis that must be ful- 
filled bj an aviatioii appumtaa, realimng tiie difficahiei 
that one ODoouiten in neeting to evolvey raise and oon- 
tral it^ gbneing faadL to see how the traveller has ani^ 
prafitahlj at the end of his journey and instmcted 
in an that it m neammrj to do^ we ahall be better able 
to af^ireciate the immeniie eflfort of those who w^re the 
creators of " heavier than air '* aerial locomotion. 

Let us at once reassure the reader we will not hark 
back to Icarus or legendary history : we will take avia- 
tion only from its modem ori^n; start from the time 
when methodical ideas were sufficiently calculated so 
that investigators were able to proceed on serious and 
rational lines, instead of aimlessly groping about in the 

The first serious investigations relative to aviation 
date only from the commencement of the nineteenth 
century, and it was the aeroplane which then occupied 
attention. By a curious coincidence, even as the first 
projected airship, that of General Meusnier, was '* com- 
plete," and in a single stroke anticipated all the necessary 



equipment, so was the first aeroplane conceived *' com- 
plete " and everything indicated by its author. 

This inventor, this incontestable forerunner of aviation 
was an Englishman, Sir George Cayley^ and it was in 
1809 that he described his project in detail in iVu^^^on'^ 

Ito. 80. Victor Tatin'B aeroplane model driyen by compressed air, which 

flew at Meadon in 1879 

Jcfwrrud. In the course of an excellent paper presented 
to the Soci^t^ des Ing^nieurs Civils, M. Soreau recalled 
this date, when he remarked how sad it was to think 
that such a valuable invention as this had not been 
possible of application immediately upon its conception. 
In fiBM5t "everything" was there in Sir George Cayley's idea 
— the wings forming an oblique sail, the empennage, the 
spindle forms to diminish resistance, the screw-propeller, 
the ^* explosion '' motor, the calculation of the centre of 
thrust, and demonstration of the &ct that displacement 
takes place towards the fix)nt. The author even 
described a means of securing automatic stability I Is 

■■■ * -^ ■ ■ '■:• >■/-'■-". '- J, *ra 


iiokall tiiat iiiftrv6lloii% aiidiBifc not m nniiinViitai meS* 

ThM it ii MOB— iiy to hmakm the ijmus of Shr Qeoy 
CSaylejr, in ktten of gold* at the biginning of fti 
hietoiyofthetaraplaM. Baridflf» the kerned B^jlP^ 
men did not oonfine hiniBetf i»^^ dnrnkkg-ptspm* : k 
hnilt the fint eppentne withiNtt e motor whidi gete Im 
feeolta fbU of promiee ; then he built a eoeand mefllaii^ 
this time with a metc»r/hot«mifix)bmalely during ^ 
trials it wee emeehed to pieoea m 1842 enotfMr 
BngKiihmeni Heneon, atteoqptod to build a modd mtth 
plane npon this prindj^ hot without eooeeee^ end om 
mnet paw on to the year 1^56 to eee tibto first eiperi* 
menta with appafatnaee that ^ lifted^** that k to eay wift 
a paaoenger on board ; it waa onl^ a matter of anetaitih 
tiim from a huge kite» hankd lij ^ vehiok^ but it waa a 
Freneh naTigator» Le Bri$^ who denied out thk imtal 
tentative effort The first attempt to glide aoriaUy by 
a '' soaring plane " was made with what was really a 
triplane by Wenham in 1866, which constituted, in 
short, the apparatus which was used thirty years later 
in the experiments of Chanute, Wright and ArchdeacoD. 
Nor must it be forgotten that it was towards 1860 that 
Nadar, Ponton d'Am^urt and de la Handelle carried 
out their '* heavier than air '' campaign, and that it was 
in 1862 that the first steam h^licopt^re was built by 
Ponton d'Am^court, a model, it is true, but a working 
model, which is preserved in the archives of the French 
Aerial Navigation Society. Another steam h^licopt^ 
a small model, due to JSrmco, driven by a email steam 
engine, weighing all told 3 kilogrammes, lifted itself 
from the ground and remained in perfect equilibrium 


without any material contact with the earth in 

The three first aeroplanes or models of a^eroplanes 
which truly " soared " were the small apparatuses of 
A. Penavd which followed the lines of a monoplane with 
empennage tail (Fig. 43) ; and the aeroplane of Victor 
Tatin constructed and tested in 1879 at Chalais-Meudon. 
The latter was driven by compressed air and its trials 
were absolutely convincing : held by a cord at the centre 
of a small circular track, it ran round the latter stretch- 
ing the cord, and lifting its weight. Subsequently in 
1906 the celebrated American physicist, Professor 
Langley, contrived an aeroplane weighing 1 3 kilogranunes, 
carrying a small steam engine, and formed of two pairs 
of wings placed, not one above the other, but one in 
front of the other, in " tandem " (Fig. 45). This aero- 
plane although it did not lift itself, accomplished the 
first aerial journey ; it covered 1^ kilometres through 
the air. A second aeroplane was built some time after 
(in 1903), it rose this time, but undoubtedly owing to 
the inexperience of the aviator, it fell into the Potomac. 
Yet the investigators were continually working, and 
two names are inscribed in the golden book of aviation, 
both well known in industry. One is that of Sir Hiram 
Maxim, the famous inventor of quick-firing guns, who 
expended over £40,000 in the cqnstructien of a very 
large steam-driven aeroplana This apparatus, notwith- 
standing the great achievement of its inventor in regard 
CO the lightness of the steam engine (15 kilogrammes 
per horse-power) only displayed a "tendency to lift 
itself," but it never actually rose. 

The other industrial magnate was M. Clement Ader, 


well known hy his great de^rdqpiieote in the ooDsfaoctioB 
of telephcmic i^ipaimtoa. In 1890 and 1896 he built 
two aeroplanes wfaidi he christened JLviotL, On both 
occasions the appaimtoses Ufted 'tkmmmkfm Jrom the 
ground^ and at Satory in 1896, befixe o ffipsi a delegated 
by the Minister of War, the ai^aratns ^fietad a figki 
ofZQQmetTtB after leaving the gmmd onder fta own eflK^ 
If, therefore, the honour of having emeeeMd the first 
aeroplane renuuns with an Eng^Bshman, the merit of 
having oonttrwAed the first apparatns that efiectivdy 
flew, rests with a Frenchman: sndi is a glorioos 
example of the entente cordidU BmodakBi with the 
history of human progress. 


Whilst some engineers were seeking " to hnsk in" 

machines for sustaining in the air, other investigators 
were compelled to seize the mechanism of the *' soaring 
plane/' and upon these motorless gliders utilising oiily 
their weight and the resistance of the air, served their 
*' bird-apprenticeship/' Foremost among these perse- 
vering and audacious men, must be placed the rightly 
renowned name of the German, Otto LiUerUhal^ who 
long before the Brothers Wright (who no more than 
followed in his footsteps in their preliminary attempts), 
accomplished some remarkable experiments in this 
direction, in the course of which he lost his life in his 
devotion to aviation science. 

Lilienthal, a Berlin engineer, built some veritable 
birds'-wings, fixed to his body, with which he sought 
to achieve the ''soaring flight" of birds of which 




, - ."^m ■■'■ *- 


we spoke in the first chapter. These wings, of which 
the photograph (Plate XYII.)! gives a very good idea, 
were formed of an osier framework, covered with light, 
stretched fabric. Two horizontal rudders, forming a 
bifurcated bird's tail were at the rear, surmounted by a 
large steering rudder of rounded form. Lilienthal, well 
poised in the centre of this framework, jumped from the 
top of a low tower, against the wind. The inclination 
of his body and legs enabled him to shift the centre of 
gravity of the whole systeuL In this manner he carried 
out some remarkable flights, some of which attained 300 
metres in a horizontal direction. After he had made 
about a thousand such Lilienthal changed the form of 
his "flier." Abandoning the monoplane he built a 
biplane and in a fatal fall &om a height of 80 metres 
broke his neck in 1896. 

The experiments of the unfortunate Grerman engineer 
were of incontestable value in demonstrating the 
efficiency of supporting surfaces and the possibility of 
realising under the best conditions equilibrium during 
flight. The Americans followed in his footsteps and 
among the first of those who, in the United States, 
sought for the solution of the problem by the study of 
the soaring plane must be mentioned a Frenchman, long 
resident in New York, M. Octave Chanute, born in 
Paris in 1831 of French parents. Chanute, although 
well advanced in age continued the experiments of 
Lilienthal. He emphasised the biplane and happily 
conceived the first disposition of the stabilisators. 

In 1899 Ferber^ captain of artillery, commenced in 
France a series of very beautiftil experimental researches 
in glides at first, afterwards in the conditions of equili- 


jrtUu.. e even tried an aeroplane £tted with a 
' manceuvring " motor, that is to say describing a circular 
>vement about a fixed point to which be was mechani- 
Jly connected. His work, his writings, place him 
ominently among those to whom we owe so much, and 
is inspiring to see a French officer occupy a difltin- 
tished position in the glorious rants of these "fore- , 
inners," who planned out the path so well. ] 

So, when, in 1900 the brothers Orville and Wilbur 

ight, bicycle makers yton, set out to tackle ' 

le problem they found 3 ground well prepared, i 
mthal had opened the ', Chanute had indicated ■ 
l6 arrangements, the Brothi i Wright perfected them, i 
nd they "strove for the t" with great judgment, | 
I, and, above all, an e; i irdinary determination to | 
come " human birds." 1 sy commenced by carrying * 
mt numerous aerial glides th their biplane 8o as to i 
secure aerial equilibriurn. These glides suggested to 
them many happy modifications, and encouiaged by the 
doyen of aviators, Octave Chanute, they built, in 1903, 
their first motor-driven aeroplane with which they fa- 
formed several flights in a straight line. It was not 
until 1904 that they efiected their first turn, &om which 
point they readily made long flights of many kilometres 
at an average speed of from 60 to 65 kilometres per 
hour. Their experiments were surrounded by sud 
mystery that many would not believe them. In France, 
Captain Ferbar, M. Bodolphe Soreau, M. Henri Letellier 
were among the few persons who loally credited the 
performances of these two transatlantic aviators ; IL 
Letellier, in view of its military possibilities, even sent 
one of his collaborators M. Fordyce to Americf^ to nego- 


tiate with the two inventors for the cession of their 
apparatus to the French Government. These negotia- 
tions were not successful and it was not until the 
summer of 1908 that Wilbur Wright came to France at 
the request of a group of financiers with whom he had 
been in treaty. He carried out his first trials at Mans, at 
the camp of Auvours, upon the Hippodrome des Hunan- 
di^res, where he executed numerous flights all under 
''experimental'' conditions: but never once setting out 
under his own effort, and without accomplishing actual 
trips. Nevertheless it must be remembered that thanks 
to his aviating skill Wilbur Wright completed some 
flights of very long duration, and among them he suc- 
ceeded in repeating the exploit of the Frenchman, 
Delagrange, by carrying a passenger with him, notably 
M. Paul Painlev^, of the Acad^mie des Sciences, with 
whom he remained in the air for over an hour. 

Overwhelmed by great publicity^ these experiments 
created an immense sensation, and one began to forget 
somewhat the French aviators when two of them 
established a record, unique to-day, and had too the 
glory of completing an " achievement " the merit of which 
they cannot possibly be deprived of, because this '' raid '' 
recorded two historical journeys in aviation by the com- 
pletion of the two first aerial, voyages " in an apparatus 
'' heavier than the air" on October 30 and 31, 1908. 



The flights of the Brothers Wright were very beautiful 
demonstration experiments, but none the less the aero- 


pLuie of the Amerioans is not perfiMst. Its sfcafaili^ 
demands a constant eflEbrt on tlie part of the aviste, 
because of the suppression of tiie empennage tail, and 
the apparatus for this reason is dangerous. In Ameritt 
it caused a serious accident to Orville Wright, snd 
brought about the death of one of its paasengeri, the 
American Lieutenant Selfridge in the aatunm of 1908. 
In the spring of 1909 the Italian Lieutenant Oslden 
was thrown to the ground through a capmae due to 
the inherent instability of his aeroplane) moreover, as 
we have said, and as we repeat, the apparatus is not np 
to the present self-starting. 

French aviators, however, were quietly working towaidB 
the solution of the problem, and to its complete solution, 
that is to say, to the perfection of a edf-starting saro- 
plane, able to rise from the ground under its own effiHt, 
and to set out agun after having landed, without eithar 
rail or pylon. 

At the end of 1903, the ardours of our audacious 
aeronauts were revived. Colonel Benard pointed out 
that year, that, if the weight of the motor fell below 
5 kilogrammes per horse-power, realisation of flight by 
means of '' heavier than air " machines would be pos- 
sible. The great authority, the sureness of the views 
of the illustrious and learned officer were more than a 
hope ; they were a guarantee for the pioneers of the air 
who set out towards the conquest of the atmosphere. 

Distinguished among the most prominent of ardent 
sportsmen Was Ernest Archdeacon, who, as far back as 
1904, made some experimental glides with an aeroplane 
among the dunes at Berck-sur-Mer. What perseverance 
was necessary at that time to pursue, without faltering, 


this struggle with the uncontrollable element ! What 
faith in the future, not to allow one's self to be turned away 
by the criticisms and the more or less witty satires of 
the detractors always more numerous than the ** actors ! " 
But the latter were enthusiasts ; nothing would stop 
them. Voisin built and tested with Archdeacon, Ferber 
and Santos-Dumont ; the latter sought to forge the 
^* connecting link " between the aeroplane and the kite. 
He constructed a biplane which could float upon the 
water, and had it towed along the Seine by the Rapikre^ 
one of the fastest motor boats. The apparatus rose, 
carrying the aviator, thus excelUng courageous efforts 
of many persevering workers. Hereafter the possibility 
of aviation was established. Also the experiments in 
aviation multiplied. 

It is necessary — it is essential — to point out that 
nothing had transpured concerning the experiments of 
the Brothers Wright, whose existence was scarcely 
known ; a stronger reason for not knowing any details 
of theb mysterious machines was that their authors 
jealously preserved them from prying eyes. Also does 
not the merit of the French aviators stand alone ? Not 
only have they done as well but they have done better. 
What more can one ask ? 

The first to succeed was M. Santos-Dumont. The 
intrepid Brazilian aeronaut was the first to carry off the 
prize which the generous Msecene of aviation established 
in 1906 ? With what is this date to be compared ! In 
1906 not a motor-driven or self-starting aeroplane had 
left the ground. One can appreciate that hje who could 
accomplish a flight of 100 metres would achieve an 
admirable exploit, and ''the prize for 100 metres'* 

Noraiiiber 12, 1906; bj a lii|^ of SaO flMtm Drift- 
ipmgs and L. UMot now Iom aftarim liie pria far 

Tbaii appeand on tiie aene twa ge nUoBiMi who ty 
Itfaair briUiaat geoflranlgr h^m gwitlj cottfanfantad 
towttds the dewelapnattk ot aerial q^ort— MIL Hiaiijr 
Daotaeh and Emeafc AnbdaaocMu The ffiriita so far 
aooomidiflhad were ia a afera%lti Itoe ; liie aviatoia liea* 

diffieoltieBy as we have already pouiled onl^ MM. 
Deutadi and Arehdeaoon cffeted a ^nm of JI2000 ta % 
first aviator who aeeompliaiied a icifremlm r IdloasakMs 
the prise was won fay Henri Farman, at the ]sfly4ei» 
Moolineaiix manoBavring gtwmid^ on January 1^ 190& 
Theraafter tiie triniiqihs of the pe t aeverin g aviator 
ocmtibned without intem^tion, and on July 6, 1908^ hf 
remaining in the air for twenty*one minutes, he won the 
prize so spiritedly offered by the engineer, M. Armen- 
gaud, to the aviator who could remain aloft for a quarter 
of an hour. 

JULY 25 1909 

All the preceding records were doomed, however, to 
be well broken by the %wo exploits of EL Farman and 
L. Bl^riot. 

Up to this time aeroplanes had simply described 
. evolutions above race-courses or manoeuvring spaces, 


wrlfeea:^, the grcfond pnrpaBdy levelkd, oflEered the best 
EMslitifiB for the lanodiflB and dfiBoentB of the Prancfa 
aeroplanflB; iheae adrsntagBGOB ocnditiimB were not 
sxM&casnt &r the Ameruxn AeraphcoflB, beoanae it wm 
neoeBsary for them to hsve also a jfyhja and kminhing 
raiL The aeroplane had tfaoB to dflmanstnite ite poaai- 
bilitieB of enduranoe, to thaw tfaact it posBBaaed really 
practical utility, and liiot it did not require qieeial 
£icilitie6 at haltrng-plafleB in itB aenal paaaage. 

It wBB MIL fi. latman and L. Si^riot who had the 
unquestioned and mdnpntahie datinctiaBQ of fblfillinf^ 

this demonstratiaii, antic^aEiiBd by the wiiole world. 
They proposed to embark upcm an actual journey from 
town to town and they smneeded. On October 30, 190R, 
Henri Farman left the precmctB of bis hangar at Bony, 
near the Chfilonfi Oaiiq>, at 3.50, and set ont for TtKftiitMa 
The wind was S.BJE1. The aviator immediatehr gained 
a h^ght of about 50 metrea, whidi waa neoeaaary, owing 
to the stretcheB of tall poplars baning bia patb. Tbus 
he passed over rrrexs, viSages, woods, Arc, and, after 
being twenty minutes on the journey, reached Rbdms, 
wliere he landed with the most perfect ease in a park 
between the cavalry barradcs and Pommery House. During 
this twenty minutes he covered 27 kilometres, which 
gave a " start to stop " q>eed of 79 kilometres per hour. 

And on the following day, October 81, 1908, Louis 
Bl^riot completed a still more sensational and mora 
perfect "journey.'' Leaving Toury (Eure-et-Noir) at 
2.50, he steered towards Artenay (Loiret), a point 
situated some 14 kilcHnetrea from the starting-point 
There he had caused to be installed some captive bal- 
loons, to indicate the point where he was to turn. 


Flying a dozen metreB above the groand, the aen>- 
plane pasBod over Ch&tean-Gaillaid and Damhroo, and 
the aatomobileB which were following him were speecUly 
'' scattered " along the roada. Eleven minutee after the 
atart a fault in hia ignition caused him to alight; he 
landed withont difficulty, rqHured his fnagneto^ and sti 
out again under his own effort^ after a descent lasting an 
hour and a half, to continue lus journey ; and now, 
holding more to the west, passed Pourpry, and made a 
second descent of some minutes at Villiers Farm, near 
Santilly. He re-started a second time, passed Pointville 
at five o'clock, and returned in quite a matter-of-fiict 
manner to his starting-point, having accomplished the 
first '' cross-coimtry '' voyage with descents. During 
this flight his aeroplane acted marvellously well, attaining 
a velocity of 55 kilometres per hour (Fig. 81). 

Louis Bl^riot thus demonstrated that the French 
aeroplanes mounted on wheels are complete apparatuses, 
truly self-startiug, practical, and capable of resuming 
their flight when it is interrupted ; he showed the ser- 
vices that aero-locomotion could render us, illustrated 
that aviation from that time henceforth could enter into 
everyday practice. 

Certes, one had been so persuaded, but a good prac- 
tical demonstration is worth more than exhaustive 
arguments : contra factum non valet argumentum. Con- 
sequently Farman and Bl^riot were absolute demonstra- 
tors, and definitely opened for us **the Highway of the 
Air " ; and it was a fair act of the Acad^mie des Sciences 
to divide the Osiris prize between Bl^riot and Voisin, the 
creators of these marvellous aviation apparatuses. 

But these exploits came to be surpassed ! By a 


remarkable flight Bl^riot crossed the English Channel 
on July 25, 1909, in 27 minutes 27 seconds. 


& Turn 

Fia. 81. The flnt " Mrlal *(i;ft([e " eSeoted Id % cloaed circle betweeo Tour; 
Mid Art«DB7 with dflMwU, bj Loaii BUriot (October 81, 1908). 

StartiDgfromBaraque8,on the French coast, at 4.35, 
his objective was Shakespeare's Cliff, but the fog com- 
pelled him to seek a landing-pmnt on the Margate side. 


Tlds adnoTonioiit lianlfitod tiis definite eooflMrt of 
^bm air hj men in tlie worid'e hkfcofy. Rngfaund and fliB 
e^f of London gn^e IBMnot a leeeption sodi ts is 
eartonded to a ▼iotonoos genofalt end this honour 
e eoo rf ed hf tlie English pabIio» wbb appreciated b^ 
tta IVenoh people. When !l^riot retnmed to Pam 
llie Franoli oiq^ital weloomed lum aa erne of its most 
l^oiiooi aona, and leoeiTod him with an mithnaaoB 
whioh win never be forgotten. 

And two days after BMriot^ on Jvlj 27^ Hnbert 
Ijttham^ on his AntainMte moncq^ane^ erMaed the Stait 
from the Fnmxk mde, bat nn&rtnnately feSl into the 
aaa when onty a mile froitt the Rigliah ooastb 

TeB» trofy I Man has now definitdy eonqoered tiie 


Prom the day when Farman won the Deutsch-Arch- 
deacon prize aviation created an indescribable enthusiasm 
among all classes of society. For a year the shops and 
vendors of post-cards sold nothing but photographs 
of aeroplanes, portraits of aviators, and illustratioDS of 
motors; the widespread publicity with which the managers 
of the Brothers Wright surroimded the experiments of 
the American aviators, helped to maintain this movement, 
and the numerous excursions of the Bayard- Clement 
airship, which on more than forty occasions went and de- 
scribed evolutions over Paris, prolonged the absorbing 
interest of the people, provoked by the success of aviation. 

At Auvours enormous crowds flocked from all parts to 
assist the Wrights' flights ; at Issy les Moulineaux the 


use of a manoBUvnng gronnd liad been veary ni^arcUy 
spared to the FiBnidi airifttoEB; another wus liberally 
placed at the difipoBitian of Idie foreign aviators ; not- 
withstanding the eaify hoar (firom 5 to 7 A-Il) that 
was imposed npaa oar investagstcra, Ijionsands of the 
corioos were always l^iere to aasiBt a £i^xt or a descent. 
Cinematographs have leprodnoed and popnlarised the 
most soocessfbl ffights ; iiie aomial revje w s have exten- 
sively introdnoed llie aeropIaDe into '&ear jnctoi^es. 

Bat it was in the imaginatiaD of Hie yo^mg Iblks that 
aeronaotical schemes were eonoeoved; tiiey dreamed of 
nothing bat aviation; at ooUege they made paper 
aeroplanes ander 12^ cover of their desks, to goaid them 
against detection faj their totor; whilst the latter, 
stadying f<nr his science degree, was occopied on his part 
in calcalating the elements ct some flying-machine that 
would revolationise the field of aerial travel ! 

Aeronaatical ccmstroction iahops sprang ap on every 
side, and aeroplane coostroctors have already issaed 
catalogues of aviaticm apparatos, '' pajraUe after trial by 
the customer,'' whilst — rign of the times — agencies have 
been established to £M»litate such transactiona 

This mov^nent was interpreted, some years ago in 
France at any rate, by the foundation of an aerial 
League^ which had the happy inspiration to have 
resort to the knowledge of Professor Paul Painlev^. 
But it has shown itself especially by redoubled efforts 
among the Societies which are so actively concerned in 
aeronautics : the Socik^ franfoise de navigatian aSrtenne^ 
presided over by M. Soreau» generally recognised as the 
oldest, since it was founded in 1872 ; PAiro dub de 
France, equally publicly appreciated, presided over by 


IL GaiUetet, of the AcacMmie des Scagnees, tite Am] 
of wliidi have been 00 fioitfvl m tlie difbnon 
developnient of aeroiiautioe m ell itrnhnnichmi^fAi^} 
nauUque CM>, fAcadkme Ah im ^v^tique dm 
^Aviation CZtifr, and oilier eodetJee have 
inereeaed the nmnbw of their membeni, At 
fAhv ChA de Bdgique^ 9ijfy fnti^^ 
a learned doaUe of MtteenOy has followed tbe 
of ita French brothera, and ia pfo gr eaai ng in a 
ahlemaiUMr. T f^ Qf^^^^YiTinfflandi ^ff^ T^ylr ^Ih ^' 
activity la manifeated. And m tnnit qieeial 
and joomala have been created; let naneeal^ fint, tleshl 
original oigana of aerial locoiaotioBy PASnnamt^, 
in 1866, and tAirapkUe^ that reaaadkaUe paper 
by ao great an anthttity aa IL QeoigeaBeaaa^oai* 

oonatitute the archivea of aerial nav^atko^ and^iv^haii 

largely drawn upon their files, with the requiaite permis- 
sion, in writing this book; to their editors we extend 
our thanks. Around them have been bom — VAiro^ la 
Revue aerienne^ la Revue de rAvtatian^ P Avion, VAmaiion 
iUustree, &c. In Belgium two excellent reviews, Za 
ConquSte de VAir and VAiromicaniqtie, have a wide cir- 
culation ; it is the same in London, Berlin, and Italy. 

And all this is the result of the triumphs achieved 
during the past few years. What is the outlook for 
to-morrow? and how striking is the consciousness of 
mankind of the value of the great inventions which are 
perfected to modify in a far-reaching manner the con- 
ditions of existence and of social life ! 

What is the future of aerial navigation! * That 
remains to be investigated in the following diapter. 



AbRONAUTICS and aviation : ApPUCATION to war, civil LIPB, 


It now only remains for us to ascertain what is the 
ftiture of this aerial locomotion, which at present is 
80 full of promise and has developed with a rapidity 
never before witnessed in the evolution of any other 
invention ? 

And, above all, it is necessary to examine individually 
the possible applications of the two forms of aerial loco- 
motion, and the two types of atmospheric vehicles — 
dirigible balloons and aeroplanes. To which shall we 
^ve the preference, and what is the future of each ? 

If one were only to be guided by public enthusiasm, a 
trifle '^ packed,'' so strenuous in exaggerating the merits 
of an invention when it '^ succeeds," as it is often slow to 
recognise it in its infancy, then aeroplanes, the last to come 
into popular favour, would be the only machine capable 
of widespread application ; the scientific writers of the 
Press have already put them to all kinds of work, and 
they hasten to anticipate all the services which they 
must fulfil in the very near future, whilst they cannot 
defend themselves against a shade of disdain for the large 

«57 R 


urehipe vhich we saw perfected "yesterday" in tbe 

ageruess for that of " to-day." 

It is oecesaary to allay a trifle this prematore entiiD- 
aiastn, which is prone to be overdone. It is necessary to 

void again, in the desire to advance too quickly, those 
(falling experiences that occurred with motor-boats when 

le ianatics hailed them as the torpedo-boats of tlie 
iuture: the ridiculous venture upon the transmediter- 
"anean race, which a Httle consideration would have 

voided, and in the course 'hich all the boats partid- 

iting, ezoept one, were lost, must serve as a lesson 

nd give food for thouj /i those organisers of too 
i^romature, sensational 

Let us say at once that he future is immense, so 

amense that it ig t to set it out in detvl 

it it will be by e* :, and all that one can actually 

Jo is to sketch out iti oad lines. 

In the first place, there must be no exclusion of either 
of the two systems, balloons or aeroplanes : botJi have 
their raison d'Stre because they correspond to dlffermt 

When it is necessary to travel very rapidly, when, 
above all, progressive development has assured the per- 
fect security of aviation apparatus, one will have recourse 
to the aeroplane, and without doubt we shall see " aero- 
plane liners" of huge dimensions, carrying nuroeroos 
passengers, securing sustentation with nothing but their 
enormous speeds. But these velocities would he truly 
attended with dangers in case of landing, or, above all, a 
" mishap to the machine," becatise, if the apparatus sus- 
tains itself by great speed, it would not have sufficient 
supporting surface to keep soaring without the motor. 



Perhaps for this reason aeroplane liners will be reserved 
even for transatlantic passages, as the ^' hull " with 
which they must necessarily be equipped will render 
landing less dangerous upon the water. Transatlantic 
journeys would then be made at speeds exceeding 200 
kilometres per hour ; that is to say, one would travel from 
Europe to the United States in a single day ! 

But when this speed is unnecessary, it appears scarcely 
possible to disclaim the envelope charged With light gas, 
this ^^ bladder," as it is disdainfully called by some 
aviators, because, if it ti*avels at less speed, it has 
nevertheless the advantage of sustaining the aerial 
navigator in the atmospher! without the li of meoha- 
nical energy. Consequently here is safety, and should 
the motor of an airship break down one is always master, 
or able to continue the journey " before the wind," if the 
latter is in the right direction, or to land, which with a 
good aeronaut wiU always be possible without very great 
risk. Moreover, an airship can carry many more pas- 
sengers ; it can convey them in greater comfort ; when 
it will have attained its independent speed of 60 or 70 
kilometres per hour, instead of 40 or 45, it will be able 
to set out practically at any time. Lastly, it can " stop " 
at any determined point in the aerial ocean, which the 
aeroplane, tributary to an indispensable sustaining speed, 
cannot do. Also, I do not deceive myself in stating 
that its career is far from ended. It has no more than 
begun, and it will develop side by side with the aeroplane. 
Let us now examine some of its applications to aerial 
navigation, and we will then see which is the type of 
locomotion best adapted to each case. 


ccunr AmjcATioKfi 

1 rr gin r] pi*! i »1 tcndcmcr 'wlutdi 
ftothnnieD todeKtrcrcBic 

tsKiB bas roBoHed, first aad 

r MriaJ narigatduu to warfiirfi. 

I ijl know haw ocm |JtaJj 

wria^ over all ot^er ocnudxiM bf As 

■17 ArigiUe, Xa/)ViMM. M leSfs wfaeoBM BD Otis 

m bad «■» «t its ei 1 ; and dHng tbav In* 

r j««a tbe ■ooosMnv ancMof the LAit^ 

4ne. rHk de Pari*, i « JZ^«Wfwr (I onit aQ 

it tike faoA) tisv« sbown irope tint Ft«Dee bas an 

Aerial zary " in being, an 3^ far tlie defenee of ber ' 


What foHD of aerial Temsl will hat serve tiie Deede 

rwaHare? Airafaipaoracro laneaf As "eombatantB^ 
or " aoouU " i 

I fear, after what I have heard fimn <Aoei8 who are 
more competent on this sulject tiiao I, that as a com- 
batant it will not often be used. Aerial battles do 
not appear imminent becaoae tiie inatallataon of aoy 
artilleiy whatever on board dirigible balloons woold be 
extremely incoDvenient; with regard to aeroplanes, their 
requisite high q>eed, and the impoesibility of " pulling 
up," practically prevent the use of caoDon except of 
small calibre. 

There is one good use for the airship in war : that is 
dropping melinite shells (or some other still more devu- 
tating explosive that may be invented) from a height 
within a fortified area or a beseiged fort. Here we are 
in the realm of the possible, and this utilisation of the 


airship is not chimerical ; it is only requisite to consider 
if the " result " would be very advantageous. 

Let us point out that the range for the projectiles 
would not be very correctly known because the balloon 
would be forced to hold itself at great altitudes so as to 
be able to escape the fire of the enemy. Moreover these 
projectiles, to produce a sufficiently destructive efiect, 
would have to be of considerable weight — 50 to 100 
kilogrammes at least. Now a balloon suddenly lightened 
by 50 or 100 kilogrammes would take much too rapid an 
ascensional a movement, and the operation would not be 
without danger to the aeronauts. So far as concerns 
aeroplanes, the impossibility of " pulling up " practically 
precludes them from this form of action without speaking 
of the certain peril which would result from the fatal 
upset of their equilibrium caused by the sudden 

Moreover, let us point out at the same time that aerial 
vessels, on the other hand, have little cause to fear hostile 
projectiles, because of the altitude at which they are able 
to float, and the aeroplanes because of their speed. 
During the siege of Paris in 1871, only one balloon 
was captured by the German troops, and then the 
pilot who controlled it was but little experienced in 

Pausing to consider the possibility of an '' aerial 
combat " between isolated units, it is certain that if two 
hostile aerial vessels met in the air they would seek to 
destroy one another ; but if they were two aeroplanes, 
and unless the gun-fire of a mitrailleuse of one put the 
motor of the other out of action, or rendered the aviators 
hors de combat, they would be unable to withstand the 


foilMirm ; ^bmt tibwe wwdd W no mmpmm, no 
tiiara woold to cttty tw» ttmdtsBMos «t^^ 

Would dirifOilfliy ahmys amwivo and ulnti^wiy ibw, 
arodli dwad tho pwawnng q pao dy aagopiMW? Idamfc 

ipoeify Mridl (ddfl^ the Mraiiai^ would avdfl hiawdf tf a 
iwiottiMtliedBEttieiiey^of triw&it^^ rwebjfliBav- 
ing out ballart ; lie would tlifla fly «p m a Tortieal bia, 
tibat is to aay^ Twy fi^idly , irfiikit the STiaton coidd od|jr 
liw oUiqoefy^ aad then ta a alii^alope, thexofajaaEaeut* 
iag JBgaage, m a woid, "irwticelly tacdmy^; anonovar, 
the motor of an aaropkiie will nrn dower and dAimt in 
aoeoidaiios with the prog r ess of ite aoosati own^ to ilie 
drareaaed mupptj of tiie oKjgsn aeoesssty Sx tii* o»h 
bastion of the gaseoiui miztaie which drr^ 
Lastly, whilst making ite vertieal imk to eome vp witik 
the aiiship, the lattor, more staUe and aUe to eaxiy, if 
not guns, at least a quick-firing weapon, or in any case 
grenades, would have ample time to riddle it and much 
more easily than it could fire upwards, the more so, 
because the artificial bird would offer to the fire of the 
airships the large target of its supporting winga 

For these reasons I fear, therefore, that aerial vessek 
will be poor combatants. On the other hand, they will 
be useful scouts, and there will lie, in all truth, their 
principal rdle in the time of war. The dirigibles, able to 
carry instruments of precision, capable of stopping to take 
a photograph or make telemetric measur^nents, will be 
extremely valuable to the chief of an army who has them 
at his command. The aeroplanes, owing to their great 
speed, will be the instruments par excellence for rapid 
reconaissances, for " raids " carried out over great dis- 


tances ; moreover, their capability of returning very 
speedily to recount what they have seen will thus render 
them more indispensable than their larger brethren to the 
general of the Aiture war. For communication with 
besieged positions the aerial vessels will be without rival, 
and it will no longer be possible to completely isolate a 
fortress, what with wireless telegraphy and a fleet of air- 
ships, or a flotilla of aeroplanes. 

With regard to uses in naval warfare, these will be 
numerous, without a doubt. A cruiser can always have 
on board one or several aeroplanes; it has even the 
mechanical energy necessary to launch them. It can 
consequently send one into the air to sweep the horizon, 
and a hostile fleet could not easily conceal itself Un- 
doubtedly submarines will not be increased in number, 
for the aeroplanes peering vertically into the waters of 
the ocean will perceive the torpedoes and submarines at 
a very great depth, whereas from the surface of the sea 
they could not be seen at all, owing to the obliquity of 
the visual rays coming from less distant points. 

Will battles then be solely decided under the waters ? 
Mystery and horror ! Let us hope that these events will 
never come to pass. 


What will be the " civil " applications of locomotion in 
the air ? Evidently they will be numerous and varied, 
and it will be possible to travel either by " public service " 
or private vehicles. 

Undoubtedly the latter will first come into vogue ; 
private airships and aeroplanes will for a long time yet 
be the vehicles de luxe, I may even say of great luxury, 


«Dd only those prinfeged hy Fortune, or those who wA 
to *ppMr eo, will be Mb to make atbU of thor iia& Bat 
^ we not eee the Hune derelojunent in the cue of the 
mtomobilel and will not the desire to ^pear, like "our 
fiiends," in • dizzy aeroplane, tam aooiety npnde down? 
without epeaking of the attraetiona of the "^teool 
oostome " which the enterprise of our great dteamaken 
will not &il to bring out at the h^^^ nKMiient» and to 
charge accordingly 1 It oannot be denied that speed 
has an irrebiatiUe fiuoination ; it produoea peculiar sen- 
sations, a veritable intoxioatirai, and to taato these senaa- 
tiona oomluned with a deoreaae in the time occupied ona 
voyage will be one of t^ next fbtms of refined luxury. 
Besides, doea not the reduottra in the length of a jouniey 
increase the avulable time £» other things, and therefoie 
does it not, in an tndireot manner, lengthen the span of 

Among these vehicles de luxe tiie aeroplaoea will be 
the " racers " : they will go rapidly ; will be able to 
carry two, three, or more persons. They will replace the 
extra-rapid automobile with which fanatics hurtle along 
at some 80 kilometres per hour; only in the air it 
will be " some 200." So &r as concerns those who are 
desirous of travelling quietly and in conqpany, and 
possessed of " the means," they will use the dirigpiUes 
which before long will proceed at 60 or 70 kilometres per 
hour. Certainly it is highly enjo3rable to have an eztenmve 
uninterrupted view. Let us point out, moreover, that if 
by a head wind the speed of the wind curtails that of 
the balloon, on the other hand, when the wind is follow* 
ing, the two speeds will have to be added ; and in choosing 
his wind — that is to say, the day for his trip, which is 


ft -., 



possible to those of independent means — one will make 
'* some 1 00 per hour " in an airship, with the addi- 
tional advantage of comfort that will obtain with this 
^* travelling coach" of the air. Then, without doubt, 
numerous hangars — " hostelries for balloons " — will be 
staked out along the great highways, and one will be 
eible to stop en route as one actually does in motor- 

Let us remark though, without delay, that for some 
time yet the greater bulk of the population will 
have to go on foot, by motor, boat, or railway, and the 
great aerial speeds will be a luxury or sport. The con- 
veyance of merchandise will always be by land or water ; 
these will be accelerated, but I do not think for many, 
many years one will consider despatching goods by the 
aerial highway. 

But one minute : there is one phase of transport — the 
"post" — which will use the highway of the air, and 
perhaps more so than we anticipate. I believe that 
before long " mail " will be sent aerially, and for this 
aeroplanes will be vastly superior to balloons. Being 
able to set out at any time, travelling at enormous speeds, 
they will carry letters and valuables ; it will be easy to 
despatch them at any time, one after the other, in all 
directions; and thus we shall have "hat- bands" for 
*' aeroplane messengers," who will go straight from city 
to city every hour, or even more often. The only inter- 
ruptions to such will be those days of heavy storms. 
Then it will be necessary to trust the messenger to 
express trains, which will travel at far greater speeds 
than now, and yet distant points will complain bitterly 
of an unacceptable delay. 


Undoabtedly dw appauanoe t^on the aeana of ami 
▼ehiclaB will profiMUidly modify the coDditions of oar 
existenoe, bat it ia not neowsary to count upon this 
change oooiiiig too qniekly. It will be some timebefcre 
m see " aero-taziB,*' and the transit in towna will be 
maintuned fin* many yean yet by terrestrial vdiietifc 
But it is oertain that bchuc d^y houBe-designer» will fed 
the neoeanty of catering fat the aerial vehicle by elevMd 
mooring^tationB. B00& will disappear in favour of flat 
terrace* auited to launching and lauding stages. Probablj, 
however, departure will not entail nuwa tlian a ibort 
start. They will be made m aUu, ^'"■^"it the flying 
apparatus will be, without • donbt, eomlMnalaoiw oCthe 
h^copt&TB and the aooplane, an. association whidi 
aasures security in the deaoanta oi the aerial vehicles is 
confined areas and at a very great a^eed ; and perhaps 
upon these flat roo& a£ iaigp hoteb -vre may eveo see 
garages for airships I What is certain is that the " future 
city " will not have quite the same appeaianoe that 
it has to-day, and wealthy residents will alwaya ton 
their ambition towards the clearer, healthier, and less 


One of the first applications of the new locomotion will 
be scientific, and more especially geographical. The 
facility of moving above all the obstacles with which the 
sui-face of the earth bristles renders it eminently suited to 
the exploration of unknown continents, to traverse which 
no means of communication exist. 

One knows how difficult and dangerous is the explom- 



tion of these mysterious countries, such as those of 
Africa, the centre of Asia, Central South America, whilst 
the torrid climate, the dense vegetation forming impene- 
trable obstacles, dangerous animals, the hostile natives, 
seem to league against the explorer bold enough to 
penetrate for the first time those territories where the 
foot of a European has never trodden. 

Also, what blanks still exist upon the maps of Africa, 
Asia, Australia, South America, and the Polar regions, 
Arctic and Antarctic, and how slowly, in fact, are geo- 
graphical discoveries efiected when it is necessary to 
explore the details of our planet by "crawling," so 
to speak, over its surface. When the explorer advances 
through the torrid equatorial regions, when he must 
toil through the bush, it is as much as he can cover 15 
to 20 kilometres per day ; this is the average progress 
of an exploring expedition ; if a passage must be cut 
through the dense primeval forest by hatchet and axe, to 
clear the way, to cross very closely tangled stretches of 
tropical vegetation the advance is slower still. When 
one explores the glacial lands of the Poles, the '' ice- 
fields" of Greenland, Spitzbergen, or of the Antarctic, 
it is not always in kilometres that the distance 
between the daily halting-points is figured, and 
in the meantime the privations and the dangers are 
as a result proportional to the road travelled over 
each day. 

What are the data which the geographical traveller 
secures at the cost of such innumerable perils ? Does he 
bring back the complete map of the country he has 
traversed at the risk of his life ? No, unfortunately, 
because in order to prepare a complete survey of a 


region it is necessary to stay there a long time, and to 
travel in all directions ; more often than not the ex- 
plorer only shows merely his itinerary, that is to say, 
only a " fringe " of the country along the path which he 
followed. Certainly he will record what he sees to the 
right or left of this route, will indicate the hills and 
mountains which he has perceived on one side or the 
other, with their distances and heights, estimated 
according to " bearings," But they will only slightly 
widen his " fringe " without giving a general map ; 
moreover, the regions described in this manner ivill be 
rather more indicated than charted with the necessary 
geographical precision. 

In reflecting upon these difficulties one can under- 
stand the existence of these "white spaces" in our 
atlas ; what is marvellous is that man has been able to 
gain such actual knowledge of the Earth, in face of this 
lassive hostility of the unknown country. 

All this time, however, although we have been 
powerless to learn the details of the surface of our 
planet, astronomers hare succeeded in gathering all the 
details of the surface of the sky, to enumerate up to a 
very extended limit the brilliant stars which are sprinkled 
above us ; in a word, they have made a map of the 

They have prepared it, moreover, through a unani- 
mous understanding among the civilised nations ; they 
have prepared it by a surveying method which furnishes 
indisputable testimony : photography. The photo- 
graphic plate, as was happily said by Janssen, is the 
" retina of the savant," but a retina which retains the 
impressions it receives. 


Up to now, certainly, it has been impossible or, at the 
very least, difficult to apply photographic processes 
to. the representation of terrestrial surfaces in the same 
manner as it was in the preparation of the map of 
the heavens ; one had, in short, no means of '' seeing 
the earth from above." The balloon, and captive at that, 
was the sole means available, and it was scarcely able to 
provide more than "local" views of the country beneath. 
Moreover, to obtain sufficiently numerous photographs 
it would be necessary to tow a captive balloon across the 
continent to be explored, and consequently to transport 
it, and his accessories, by means of a caravan ; up to 
DOW this difficulty has never been overcome. 

To-day, on the other hand, the dirigible balloon 
furnishes us with the solution so much sought after, and 
I believe that it will fulfil it in a complete manner, thanks 
to the addition of topographical photography in the 
form so excellent and so precise devised by Colonel 
Lauss^dat about 1852. 

Let it be pointed out at once that taking only the 
road traversed, and even if it were kept within certain 
limits, the dirigible aeronaut-explorer, by vertically 
photographing the earth above which he manoeuvred, 
would be able to obtain a route survey of a superior cha- 
racter to that which explorers travelling over the surface 
of the ground would be able to procure. Indeed if, for 
example, he stood at a height of 1000 metres while 
photographing the earth underneath with an apparatus 
of which the wide-angled lens had a "field" of 90 
degrees of angle, and a focal length of 20 centimetres, he 
would thus have a photograph which would be a topo- 
graphical map on the scale of xj^; but this map 


would be both exact and complete. Numerous photo- I 
graphs would be able to be obtained, and by placing 
them side by side one would thus have the detailed and 
correct topogi'aphy of the route followed by the airship; 
as, moreover, the latter travelled at 58 kilometres per 
hour, the explorer would take in one hour more maps 
than the ordinary explorer would make in three days, 
and it would be done without danger, without fatigue, 
safe from the attacks of natives, and protected above all 
&om the onslaughts of poisonous insects, from marshy 
miaemffl, which are the greatest enemies against which 
explorers have to contend. To-day a balloon (as the 
Zeppelin has demonstrated) can travel for 38 hours 
without descent ; therefore it would be able to make an 
outward journey for 19 hours, with 19 hours for the 
return journey, stop for the night, and in this manner 
explore the country within a radius of a circle of 
1000 kilometres, which would take a traveller from 40 
to 50 days to pass over. 

But by this simple means, notwithstanding the 
already very marked superiority of an aerial voyage 
from the point of security, speed, and the data obtained, 
one might wonder whether the results would justify the 
despatch of a dirigible to an accessible point of the 
continent which it is desired to study. But then one 
can and must rely more and rather upon the collabora- 
tion of the dirigible and the camera. 

Let us state at once that the dirigible will be greatly 
improved within a very short time ; its present speed 
of 50 kilometres per hour will be easily increased to 60 ; 
its volume will be augmented, and in place of 3000 to 
3500 cubic metres it will be given 5000 to 6000 cubic 


metres while still preserving its '' elastic '* construction 
and not falling into the drawbacks of the rigid baUoon ; 
already an airship of this volume is under construction 
in Paris. If, under these conditions, one is content with 
a speed of 50 kilometres per hour, which is magnificent, 
one will be able to carry sufficient fuel for a continuous 
Toyage of 50 or 60 hours, which means 25 to 30 hours 
for the outward and the same for the return journey. 

But in 25 hours a balloon travelling at 50 kilometres 
per hour would cover 1250 kilometres. It can descend 
during the night when photography is impossible, set- 
ting out again the next day and even stopping en 
route if necessary. The perfection of the special 
balloon " fabrics," the judicious use of the air-ballonnet, 
enables the balloon to remain in the air without any loss 
of gas, and the airship Patrie which was perceived 
floating in the North Sea ten days after the storm tore 
it firom its bonds, shows the strength of the modern 
airship. We anre able to say that there is in course of 
realisation^ in the field of aeronautical construction^ air- 
ships of from 5000 to 6000 cw6ic metres volume, and 
having from 1000 to 1200 kilometres '^radius of 

Consequently, in choosing convenient " centres " for 
establishing aeronautical stations, centres which will 
coincide with inhabited and accessible points to which 
one can easily convey the material axid personnel, one will 
be able to cover a continent with a network of circles of 
fix)m 1000 to 1200 kilometres radius, each of which can 
be traversed in 20 or 25 hours, by an airship carrying 
the explorers and their instruments. Fig. 82 shows how 
one can apply this system of exploration, which is so 


s base, have their optical axes turned 

point, one has a triangle, the two photo- 

lultaneously from which enable one to 

1 structure. It is in fact " plane table" f 

keying, with this difference, that instead 

the graphic work upon the spot, one 

nd with him " and completes the work i. 

nethod is even capable of simplification. 
3 at the two extremities of a " base," 
ich is absolutely known, two cameras, 
vhich have their axes absolutely parallel, 
3ir shutters at the same moment, which 
latter with a battery and two electro- 
these two photographs one could com- 
e country up to the limits of the visible 
I of Dr. Pulfrich's remarkable instru- 
rnpa/rateur^ buUt by Zeiss, the eminent 
►f which is retained in the museum of 
5les Arts et Metiers. A most renowned 
i. Professor, 0. Hecker, of the Potsdam 
"te, has shown how one can make the 

sneous use of the parallel two cameras 
-ae of known length is essentially pes- 
rigible of the Bayard -Clement type, for 
f cS and indeformable car, of which the 
» will be the base, the two cameras will 
^3d at the two extremities, and their 
one and the same time definitely 
Qe. The photographic data necessary 
f the map by the aid of the stereo^ 



t , 

1 1 






■ r: 

f ■!. 

• Ii 

s > ■■ 



simple, so rapid, and so safe, to a prescribed re^oa; to 
the African continent, for example. 

The centres indicated are accessible ; two are in Frencli, 
two in English, and one in Belgian territory. They are 
Timbuctoo, the shores of Lake Tchad ; Leopoldsville, for 
the Belgian Congo ; Dongola and Lake Albert for the 
glish stations. In tracing round the centre of these 
circles of .1100 kilometres radius it is seen that the whole 
af Central Africa can be covered thereby, and the circles 
Day even " overlap." The exploring traveller in hia 
lirigihle, therefore, can actually touch every part of the 
inknowD country. The provision and the maintenance 
f the aeronautical stations can even be dispensed with 
r the immediate return journey, as it can halt at a 
different centre to that from which it set out, which 
might be of great value in case of an unexpected storoi. 
In this instance I have confined myself to Central Africa; 
hy adding a si.xith centre at Dakar the whole Mauretania 
would become " explorable." 

Would the airships which accomplished these expedi- 
tions be limited to securing " route photographs " ? No, 
they would do much better, thanks to Colonel Lauss^t's 
process, the principle of which I will explain in a few 

In 1852, Colonel (then Captain of En^neerB) Lauss^at, 
impressed by the adrantages that photography would 
afford in the compilation of maps, evolved a means of 
preparing topographical surveys by means of Baguerre'a 
invention ; for this purpose he employed not one photo- 
graph, but two, taken from the extremities of a long- 
known so-called base. If one knows the angle of the 
lines of vision of the two apparatuses which, from the two 


extremities of this base, have their optical axes turned 
towards the same point, one has a triangle, the two photo- 
graphs taken simultaneously from which enable one to 
build up the actual structure. It is in fact '' plane table" 
topographical surveying, with this difference, that instead 
of carrying out the graphic work upon the spot, one 
" carries the ground with him " and completes the work 
at his desk. 

This excellent method is even capable of simplification. 
It suffices to place at the two extremities of a '^ base/' 
the length of which is absolutely known, two cameras, 
the objectives of which have their axes absolutely parallel, 
and to actuate their shutters at the same moment, which 
is a very sunple matter with a battery and two electro- 
magnets. From these two photographs one could com- 
pile the map of the country up to the limits of the visible 
horizon by means of Dr. Pulfrich'8 remarkable instru- 
ment, the stereocom/poArateur^ built by Zeiss, the eminent 
optician, and one of which is retained in the museum of 
the Conservatoire des Arts et Metiers. A most renowned 
Grerman Geodesian Professor, 0. Hecker, of the Potsdam 
G^odesical Institute, has shown how one can make the 
most of this process. 

And this simultaneous use of the parallel two cameras 
at the ends of a base of known length is essentially pos- 
sible on board a dirigible of the Baya/rd-Clernent type, for 
example. The rigid and indeformable car, of which the 
length is 28 metres, will be the base, the two cameras will 
be permanently fitted at the two extremities, and their 
distance apart is at one and the same time definitely 
known and invariable. The photographic data necessary 
for the compilation of the map by the aid of the stereo-^ 




itttd Ui tluf> nmmi i^r tt *nll bo JoiiKsr lie merely jibflbK 
pntpiib of iiw sul^aaaiii pvnud iHms. &t manmaait idl 
isiuf^lAck witli tlMtm: tkew- mrt tht aan^iaatf fMtofir ;| 
ft *' j^tft^n^ibiai! map " ■§ &t as tbe litnit ^ iflH «ilHl | 

iBCtiy " fixed " 'ood 
vercicbUv BJid iii £t 
tauce far plsjiitnetiT 
TboB a few anal 
expadioooB made a ] 
tike ioierior of cne rf I 
tbe ofdee of wiud { 
WQ have qxifcgn ii3 
iDore tliui Boffioe H 
iuiBishthemapoftbB ! 
entire coontiy a- ! 
duded therein. 

But in order to 
render this endeavour , 
practicable, the aaa>- 
tance of several j 
natiotm iH necessary : the map (Fig. 82) shows that ftv 
Central Africa that of France, England, and Belgium 
would suffice. The cost of an expedition of this nature 
will t>o infinitely less than that attending ordinary 
exptMjitiotui acliieviog the same results ; the time 
will be perhaps one hundred times leas, the predsira 
will be superior, and the dangers very appreciably 
diminished. • 

So far as concernB the country adjoining the fVench 
North African posBessiooa, no places would be misaad 


Zr^^i^ ' ASIA 


rS^ ^ 



\ "-^ 




\Jfc' V-J* f V 


S^^^wv' ?* 


\ /^ 



rw, tZ. TV «i|<lvntMW vt Cednl 
AIrk* bj dirigible 


where one would be able to establish dirigible 

This system of working is not only applicable to Africa : 
"tike whole of the " Matto " of South America, the interior 
of Australia, as well as of Asia, would be able to be 
explored in this manner with material results through the 
co-operation of the interested Governments, and it will 
thus be possible to complete the ^* map of the earth," 
which, indeed, is the least that might be done, inasmuch 
as the photographic map of the heavens has been carefully 

With regard to the North and South Polar Regions, 
undoubtedly it will be in this manner, and in this manner 
only, that we shall be able to learn their geography 
completely and rapidly. We know how slowly explora- 
tions are able to proceed after the vessel is left — that is 
to say, in the same manner as one explores a new country. 
It is only by heroic eflfort that polar explorers have made 
their perilous discoveries. Consequently it will be by 
dirigible that it will be possible to study the glacial 
regions, not only in the vain curiosity " to reach the 
pole," but to learn scientifically the geography of the 
axial caps of our terrestrial globe. To have dreamed of 
this five years ago would have been madness, but in view 
of the achievements of the airships Patrie^ Bayard- 
Clement, and Zeppelin, it is a feasible achievement. The 
distance from Spitzbergen, where one would be able to 
have a station, to the North Pole, is only 1300 kilo- 
metres (720 knots). It is thus within the limits of 
possibility of actual dirigibles, when they have been 
perfected. Likewise, to solve the problem of the complete 
exploration of Greenland, a station at Uperniwick would 

Cnnitfiii ftr aahtf tm A« ■ bjj i ^u 
Umb i1<— !■ of in^ dHthiMcer •■ 
utHy dfntnd Ifae sae ef mmrt^ 
•oatber at aome dirtaaee^ sad cfhie at ertaodiHg: 
muiaal — itttnfe is eaae of neeesity. So &r as t^ 
Antarctic ii ooncerned, its exploratioa wtjold be 
difficult, otriog to tbe extent of ita nr&oe^ and, wJtmt 
all, the remoteoeH of its shoreB from riTiTiaiifinii 
would be neoe— aiy to establish qiedal statkna, and Ai 
" raids " that would have to be carried out by the m- 
■hips would exceed 20O0 or 2500 kilometres outward, as 
well aa return. Undoubtedly, nherefore, this will be 
the last part of the terrestrial globe that will be made 

Be that as it may, the 'aerial exploration of unknown 
onntinenta is quite possible l^ means of dirigibles. I do 
not think that aeroplanes will take part therein so long as 
tlipy are not provided with sustaining screws to permit 
thorn to remain in the air, and in their present form their 
iint"^i'*'^>'''^y °^ "stopping" prevents recourse to photo- 
(iijtntfi-aphy by them. But they will be valuable auziliuies 
it) the iense that by rapid reconaissances made at 
hitlli Npeeds, they will be able to indicate the most 
iB^raibing points of which it will be useful to have a 



detailed map, and upon which the dirigibles, after their 
indication, can be engaged. 

One other application of dirigibles and aeroplanes, a 
sphere in which their use will be extended, is the necessity 
to learn, by careful study, the laws of atmospheric 
orculation in the highest and middle altitudes. As a 
matter of fact we scarcely know the laws of this move- 
ment in the inunediate neighbourhood of the earth, and 
but for the work of the Prince of Monaco upon the ocean, 
and those of M. Teisserenc de Bort by means of kites, 
France would be very much behind other nationa 

If it is desired that aerial navigation should develop as 
it ought, it is therefore urgent to pursue the exploration 
of the higher atmosphere, and the further knowledge that 
we shall acquire in this way will be completed, if not ex- 
clusively furnished, by savants travelling in dirigibles 
and aeroplanes. 


Not one of the least benefits to locomotion through 
the air is the creation in a few months, as if by the wave 
of a magic wand, of a new industry, and the development 
of a considerable commercial movement the significance 
of which it is impossible to indicate. 

In the first place the generous initiative of M. Henry 
Deutsch speedily found many imitators : there are actually 
over £64,000 offered to aviation in France alone. More- 
over, the Osiris legacy endowed aeronautics by £4000, 
which the Academic des Sciences divided between the 
constructors, Bl^riot andVoisin, and, through the generous 
and active initiative of M. Barthou, Minister of Public 

X80M ilmdy «M, Mi gbift 

uaCUbiwf JKmotA Imad£ticMtat 
JgfOwl-CTfcmiif, JMjpi'fB, aadAuM (bdim] 
ynMkOfB). That totak in kD te* i 
boOt in i>ur yo^n. Wb«o one r 
OD tba menge £12.000, that makoB XU(M>00 ; 
BOntiMaX120,000 if ooetakeBintoaoooiuit tiiepon^ei 
Mid tbe moDej expended tipon experiments. I do not 
take into ooiuideration the numeroos efibrts <^ HH. 
Santoe-Uumont and Comte de la Yanlx ; of the attempts 
of MU Mal^tt Mar9a7, and others; by adding all 
together one obtains for tiiis period of in&ncy and 
ex|>erimentB something like £400,000- This is an economic 
aapeot of the question that one must not overlook, espe- 
oially if one reflects that we are yet only in the early 

And aeroplanes I It is by tb6 hundred that one nov 
oountu their ooostniction ; the money circulated for an 
aviation apparatus is less than for an airship, that is 
pertain, but it la precisely for this reason that a veiy la^ 
number of persons are participating therein, and it is hj 
hundreds that it is necessary to enumerate them at tliis 
moment. If one admits t^t each, including the tmk. 


represents an outlay of £800 (and we under-rate the 
truth), we thus arrive, under this head, at many thousands. 
And here it has heen more rapid since the true experi- 
ments in aviation do not date back more than eighteen 
months. If one keeps account, moreover, of the money 
expended in fruitless experiments, in repairs, in expenses 
of all kinds, the balance-sheet of aerial navigation, both 
dirigibles and aeroplanes, shows a money movement 
daring the past five years of more than £800,000 ! That 
18 excellent for a start. 

And this is only in France ; the whole world knows 
that Grermany has expended enormous sums upon its 
military dirigibles : it exceeds 12,000,000 marks already. 
In England, the United States and Italy the movement 
18 equally important. Aerial locomotion has therefore 
given birth to an industry which appears likely to 
undergo a tremendous expansion. This industry creates 
a financial reflex because in France alone ten limited 
companies have been actually established, representing 
a total capital of over £200fi00. There are many others, 
also very important, abroad, and the Bourse is entangled 
because, rightly or wrongly, speculations have already 
taken place in these new stocks. 


Now what progress remains to be accomplished in 
order that aerial locomotion may maintain its excellent 
prospects for the future, in order that new conquests may 
justify the enthusiasm provoked by its glorious d&mt ? 

In connection with dirigibles the first condition will 
be to obtain at once the speed of 60 kilometres per hour 
at least, so as to reduce to twelve or fifteen days per 

year the period of compulaory idleness- It will then be 
Decessaiy to increase their volume so as to altov 
the increase of fiiel-carrying facilities for participa- 
tion in lengthy voyages ; in a word their mding of 
■ action must be extended to 1000 or 1200 kilometres; 
I consider this indispensable. Then it will be available 
for armies and exploring expeditions, of which services 
we have already spoken. 

But as the possibility of any accident to the motor 
must be prevented, it will be necessary to provide them 
with two independent engines and two propellers ; in 
this manner the failure of one engine would not bring 
about disablement, or compel landing at some place 
where an accident might result. The balloon fabrics 
will be still more perfected, and will assure to an airship 
the possibility of remaining inflated in the air for fifteen, 
twenty, or thirty days without taking another charge of 
gas. Their construction will certainly be improved, and 
one will learn the best means to avoid the cause of that 
" fermentation " of the rubber which is incorporated 
therein, and which may render the dirigible's envelope 

But one thing which will be indispensable, in fact 
necessary, will be the construction of garages, landing 
stations and shelters ; by this means, and by this means, 
only, will the airship render great service, not only in 
France but in the colonies. 

With regard to aviation apparatus much remains to 
be accomplished. At first it will be necessary to in- 
crease to a great extent their security, and to assiire 
their lateral and automatic equilibrium. We haw 
seen that it is compulsory to increase their speed up to 


150 or 200 kilometres per hour, velocities which we shall 
witness soon without a doubt. And at the same time 
it will be necessary to reduce the dangers of shocks 
at landing, dangers which will increase in proportion as 
the supporting surface will be diminished, because of 
the progressive increase of the speed of the aerial 
vehicle. It will be essential, more so than in balloons, 
to equip aeroplanes with two independent motors, each 
of which cdone will suffice to assure sustentation and 
propulsion. In this manner only will it be possible 
to reduce to the minimum the risks of an aerial 
journey. The number of the devices for steering and 
control of the motor must be restrained to the minimum, 
80 that the pilot has less to do ; the facilities for accom- 
modating passengers must be improved; it will be 
necessary to increase the radius of action which scarcely 
equals two or three hours' actual travelling at 80 kilo- 
metres per hour ; special safety arrangements for cases 
where the aeroplane would have to descend upon a lake, 
a river, or the sea must be provided. 

And above and before all, the necessity of launching 
from level ground must be suppressed, as such may be 
unavailable, as, for instance, in a mountainous or forest 
country; if this obligation be persisted in, it will be 
a serious obstacle against the general application of 

This is the goal to which the efforts of the investi- 
gators must now be directed. Flying machines must be 
able to " rise from the spot " ; then they will have an 
immense future, and maybe we shall see aeroplane-lingers 
ploughing the air with numerous passengers, whereas as 
yet we have only aeroplane birds. Possibly this deve- 

nil ilM|,Trii Ifi iMjwIffi 


! to HMj tf ffe Sv^qpeaa^lM 
I Ma, ^Mfa to the iinl • n, dtrnt of Urn haa, 
taac tke liiwiali, to iii^iiiw tli^ and to 
r! Tkmt dmnain oT the air, wiiA 
I pnUilad to Unfile fcaa peoetimted, aooo iri& 
gwcra rt ■• he boUl sv^npoa tlie earth, as be p«- 
vaiW ttpoo sad nnda the watczs ! Certainlj the histoiy 
of all bis ODoqnests b magnificeDt, bat I think tbst 
nodoabtodljr the niost fascinatiDg is that which we hare 
described ; it is that by which man has at last freed 
himself froizi serritiide upon terrestrial soil ; he has 
brokea the fetters that the laws of balanced weight 
imposed npon him by the speed of his machines, and 
now, henceforward &ee of all shackles, be will be aUe 
to dash without hindrance along the " Highway of the 



Tli« tihnut P moving »gpinA tiw obiiqae aorface ia <L4ii e —!J 

(2) p = ^sy«/(i) 

/(i) hmg an aistum of the angla i. ISiiH action ib ample nul 
mttit be of tke fbrm 

/ (*) = X am i. 

Wilb regasrd to the ^ne of X, it ia given by Sormnla which £fo 
• gco f dia y to the mtmmUM who hsfe emtnciated them. Hsce an 
the three which aie the most used : 

^^ ^ "^ H^Liii (Colonel Dnchemin) 

(4) X » a - (a - 1> m* i (Colonel Benini) 

in which a is » number between 1 and 2 aztd more in the oeigb- 
boarhood of 2 ; 
and hctly, 

formnla in which m is the ratio, , " , if one calls 2/ th€ spread of 

1 + A ^ 

th« Bnrface and 2A ita dimension in the direction of travel; m 
c^inHef|nently depends apon the elongation of the surface as well 
as X. 

At all fjvftnts X varies with the angle i. Let us call Xo its Tn^aa 
value and let ns admit : 

K = Xo 

w(^ have tlien for expression of the normal thrust bearing npon a 
flat Hail, in the case of an angle of attack small enongh to draw it 
without confounding the arc with its sine : 

(6) P = KSV«i 

ihn angle i was expressed in the function of the radius. 

N.n. — Many authors often confound K and ; it is important 
to avoid this confusion. 


{C) Position of the Centre of Pressure (or centre of thrust). — 
In reverting to Fig. 48 which graphically expresses as the result 
of experiment that the centre of thrust is drawn more to the front 
edge of the moving surface, one has to calculate the distance d 
between this centre and the centre of the diagram of the moving 
rectangle, the formula conceived by the engineer M. Soreau. 

^^^ ^ = 2(l + 2tgi) 

2h being the dimension of the rectangle in the direction of travel. 
Avanzini's formula, a little simpler, is the following : 

(8) d = 0-6 A (1 - sin t) 

(D) M. Berget's Speed Formula for* Dirigible Balloons. — 
This formula is 


in which V is the speed in myriametres per Jumr, F the engine 
effort in horse-poweTy S the surface of the maximum transversal 
section in square metres, and G the coefficieiU of advantage of the 
airship (see Table on page 118). 

{E) Measuring the Speed of Aerial Vehicles. — ^This operas 
tion, indispensable to aeronauts, and which will be to aviators also 
as soon as they can undertake voyages of some duration, is simply 
effected by means of the apparatus of the engineer Joanneton of 
which front and back views are shown in Plate XXI. 

The apparatus is a copper quadrant of which one face carries 
an engraved *' table " over which moves a rule. This rule indicates 
by the aid of ^-ratio gearing, the part of the angle at which turns 
a mirror with which it is solid and which projects from the back 
face. The aeronaut by the aid of a small telescope sees in 
this mirror the image of some arbitrarily chosen point upon the 
ground (a tree, steeple, building or what not) and follows this 
object for one minute while turning the mirror in such a manner 


Uistthe image always rests ia the field of the teleaoope. There U 
nothing more to do than look upon the " table," to see the inter- 
sectioa of the role with the line of altitude ehown by the barometer; 
the abscifisa of the correBpoadiog point indicated upon the hori- 
zontal edge of the quadrant gives the epeed in kilometres per 

The apporatna weighing about one kilogramme Baspenda itself 
by its weight in the desired position : it is snScient to hang it np 
by a cord and a ring to the soapensioa ring of the car. 


AOAD&KIB a^rooantique da ftanoe, 25<{ 

Ader. 248, 244 

Aerial League, 256 

•• Aerial yachts," 77-79 

A^ro, 1% 256 

olnb de Belgiqne, 256 

club de Franoe, 256 

-M^haniqne, \\ 256 
A6ronante, V, 256 
A^roDaxitiqne-clnby 256 
A6rophile, 1', 256 
Aeroplane*, 164, 268-66, 276, 277. 278 

accidents in, 176,178,197 

AntoineUe, 219-25, 284, 280 

biplanes, 189-41, 187-205 

B16riot, 141, 201, 206-14,250, 251, 252, 
258, 254 

body of, 166-67, 207, 220-27 

chassis, 211, 219, 228 

CUmerU'Bayard, 225-28 

oonstmction, 157-86 

oonstmction of wings, 185-87 

descent of, 155-56, 194, 228,224 

elevating rudder, 151, 189, 195^ 203, 
205. 212, 216, 217, 218, 22% 227, 

faU of, 155 

Farman. Henri, 141, 166, 168. 187-91, 
283, 250, 251, 252, 254 
Maurice, 201-204 

Gaitambide-mengin, 141, 220 

landing shores, 194, 222, 223 

launching, 152-54, 198, 201. 219, 228, 

launching-xaU (Wright), 154, 198, 201 

Maxim, 248 

monoplanes, 189-41, 206-289 

partitioning of, 146, 147 

Aeroplanes — conHnued 
propellers, 168-66, 190, 198, 204, 208» 

210. 228, 227, 229. 285, 287, 288 
regulating speed, 126, 178-78 
SafUnt-Dumant, 141. 280, 249, 250 
security. 178-78 
self-starting, 152-^. 201 
Skates, 194, 228, 224 
spread, 186, 187, 188, 192, 202, 207, S0» 

215, 221, 227, 229, 237 
stabilisation, 188-34 
stabilisation empennage, 182, 188, 188, 

202, 207, 218, 222, 238 
steering-rudder, 150, 151, 188, 195-98, 

202, 205, 208, 216, 222, 227. 229 
Tatin, 100, 225-28 
turning of, 141-44, 286 
VerMme, 225, 228-280 
warping wings of. 145. 194, 195, 196 

202, 216. 229 
Wenham, 242 
wings, 185-41 
Wright Brothers. 187. 141. 146. 146, 

151. 158, 164, 166. 167, 192-2^01, 202, 

214, 225, 280-81, 242, 244, 245, 246, 

247, 248, 249, 254 
Ailerons, 144 
Antoinette, 221, 222 
Bl^ot. 146, 207 
Air, atmospheric density of, 4 
ballonnet, 26, 27, 28, 36, 37, 42, 83, 84 

co-efficient formula of resistance, 15, 

Oonqudte de 1*. 266 
resistanoe of. 14, 126, 129 
transport, 257, 258,259, 263, 264,265, 866 
▼agaries of, 122, 178, 174, 175 



tfiMM^ftV*^ M. «>. M. K. •«, «B. 

Tt-n. a. U*. Ml HL «■. SU. 

Omm« «• te T^b, «, Hb i^ Ml, 


AvMt, b, to, tS-M. H. lis, UI. 1», 

Omw«l MauBUr'a, R-M 
Oarauo. W. 21. 71. IIM-IOS. 370, z:« 
GI9ud'a.«, IT, It, E«-U, lU 

InjiroramaBU M b« affaeted in, IIS- 

IIS. 2T(I-M 
iixlepMutMit apMd, 4S-SI, M. BT, V3. 

lo4u.trr, 2T7-27B 
iMiiilliiK of, 72, 7»-TC 
lAlmuty, to, He^», S78 

InDKitiiillnkl ■tablllt}'. S3-37 
rutin«>UTrIn|[ nf, 06, 70-75. 79-81 
mlllur)' ait'llcallon*, 280-281, 279 
"niunrinft" ftrruigemeut for, 7J'7S 
Rli'ton, K, Aa-86, 89, 92, S4, 95 
JV«Hi *cun.iu», ILS 
f'lruvnl, 108 

/>alri<, la, 40, 44, 73. 99, SSO, 271 
{iruiwllDn. 09-48, 09, 84, 8S, ISS 


fpHMAai^ n, SI, IKBI 
■otw^ IM. iM. in. SI as-a 

A^ pdBt 0*. 41-4*, 81, M 
ARfadMCOB. 2U, SW. 3S1 

of. j,m 

Anatioo. 119 
clafai, 2S5. SH 
OeoUch prii«, 2S0 

motora, 203, 204. ZIS 

r (jounui). 2ea 

Babiskt, 179 
Ballftft, 5, 202 
BAlloiuiet, Bir, 26, 27, ! 

S4. 88, 96 

tulvantage of lai^e voIoom of, IS, 

diiiineas in, 80, 81 

hugarB, 70, 71. 106, 2S5. 286, SSD 

leulicular, 183-1S9 

I, 36, 37. 41 




lifting ropes. 61, 62 
Montgolfier, 18, 82 
mogpeoBioik parallel, deformable, 62 

triangnlar, indefoimable, 62 
weighing, 71 

»o, Leon, 278 
LoniB, 277 
f, 108 
[et. A., formula of, 110-113, 287 
Aeronautical exploration project, 266 
ly Georges, 256 
.JBicjole, comparison of French aeroplanes 

with, 283 

flight, 119-124 
wings, 121 
316riot, L., 141, 146, 168, 167, 201, 212. 
218, 250 
Channel flight, 218, 225, 252-54 
monoplane, 146, 207-214, 234. 251-54 
^ladskj, de, 80, 96 
JBiegaet, Louis, 204, 235, 237 

Caillstst, 256, 285 
Caldera, 197, 248 
^Capacity sastaining, 137, 188 
Otpazsa, 75, 80, 183-186 
Oar, construction of, 64 
Oaylej, Sir George, 240, 241, 242 
Cell, rear, 188, 191, 202 

central, 188. 191 
Cellular type, 187-192 
Centre of gravity, 23, 24, 180 

of thrust, 23, 24, 130, 131, 132 
Chalais-MendoD, 55, 93, 94, 180, 225, 243 
Channel, flight oyer — 

Bl^ot, 225, 252, 253, 254 

Latham, 225, 254 
Channte, 201, 242, 245, 246 
Chanvi^e, 68, 204, 226, 228 
Civil life, applications to, 263-266 
Clement, M., 41, 102, 225 

'Bayard aeroplane, 226, 227, 228 

-Bayard dirigible — mu Airships 
Clerget, 79, 227 

Co-eificient formula of air resistance, 14, 

of advantage, 110, 111, 112, 118, 287 

Colardeao, 285 

Colonel Renard, 7, 9, 11, 17, 37, 38, d9» 
44, 48, 49, 60, 67, 90-94, 115, 137, 
163, 167 
airship, 102, 278 

Comparison of aerial with marine naviga- 
tion, 12-16 

Conditions of eqnilibrinm, 23 

Conqoete de I'air, 256 

Construction of airship, 59-81 
of aeroplaw», 157-186 

Comu, 235, 236. 237 

Critical speed, 38, 89 

Cylindrical shapes, 17, 18 

DxFOBMATiON of envelope, 34, 35» 

Delagrange, 141, 190, 191, 192, 247 
Demanest, 224 

DemoisdU, Santos Dumont*8, 280 
Descent, airship, 72, 73, 74, 75 

aeroplane, 155-156 
Deutsch de la Menrthe, Henry, 94, 100 
102, 250, 282 

aeronantical prise, 95, 96 

aviation prize, 220 
Deviation, 41 
Dizziness in airship, 80, 81 

dirigibles — tee Airships 
Dnpny de Ldme, 17, 44, 88, 163 

BiFFBL, 285 
Empennage, 39, 40 

craciform, 41, 99 

pneumatic, 42, 1 00 

sUbllisator, aeroplane, 132, 139 
Bnrieo, 242 
Envelope, profile of, 59-61 

deformation of, 34, 35, 36 
Equilibrium, dynamic, 37 

of dirigibles, 23, 25, 26 
Esnault-Pelterie, 141, 151, 158, 160, 166 
167, 169, 212, 230 

aeroplane, 218-219, 225, 228 

motor, 214, 218 
Explorations, aeronautical, 266 

elevating rudder — $ee Airships and 


FAniAF, Haoil HI, IM. ICa, IflT'ttI, 
m. 350, *». US, SSI 

Taibtr.ChpiBlB. !»;, Mi, US 

flmiDB. IM. 131 
•^^ ISI-I22 

FttmaU, B«|M'a dirfglbl*, I1(»-IIS. 

rormiil*, RMeoMtlMd, SSB, 9H, 3S7 
Fonndai, ZI4 

J>n->n, U, *Q. M-ML M. US. 151, IM 
- FriBKe " ootnctias. 1», IM 


-MeogiD aerofJuie, 230 
Gtognphi. Bpiplic&tion W, MS 
OiAkrd. Henrj, 9, 17. 41. BS-SS. ISS 
Oinh tatpetuaoa, S2, U 
OtUiiig. 173, I8«. 121. SU. 2i5. 248 
Uodud, lOB 
Gndtj, oeolre ol, 130 
Giou. Ton, 108 

mllit&rr kinhip, lOS 
GyropUiie. Bregaet, 201, 205. 23S. 237, 

OTToicope, SB. lis, 119 

efTecti. 69, 118. UB 

HA!cgA£8, ballooD, 70, 77, 106, 365, 266, 

HArgrakveg, 140 
H&dU. I>,ie3, ^38 
Hilicopl^rei, 120, 178,212, 213 

antomolor, ISO 

Btegaet. 235. 237, 238 

Cornu, 23C. 236 

de U Laodelle, 178, 213 

Liger, 181.235 

PoDtOQ d'Ameconrt, 179, 213 

Renard'a cotDposite, 180, 183, 335 

Ibne-powei^ 10. 11. IB, IS 

-bom-. II 

bonr. w ei g ht per. 11 

voifhtper. 10. M 
HonM de VillcBra**. IW 
Brdnga^l. 5 


iMtnmttio, dijlgtbla g^dbf> 'M^ 

KjprfcKKS. 75. W 

KltM, 1S6-199 

oallolu'. HO, 111 

eqnUibriBtn, 1 25. 123 

Haifitarss, 140 

■UBlUple. ISB 
Krebs, 90-91 

LA HAUI.T, 18S-288 
UndeUe, de U, 179, 24S 
LADglej, 213 
Latham. 200, 224, 225. 231,131 

Chaonel Sight, 22S, 2£4 
XADDchiDg an •CToplano, 1S3-1M, IH> | 

219, 223, 230 
Leagoe. aerial. 2fi6 
Lebaad}', 96. 97, 99 

airehlp.40. 14,97, 98, 113 
Lfl Bria. 212 
L^er, 181. 235 

Lentlcalu balloon, 1 S3, 181, ISS, IN 
Letellier, Henri, 216 
U'/erU, 100 
LiEting ropes, 61, 62 
Lilientbal, Oito, 201. 214, 345 

Malecot. 27B *J 

pallet, 202 

MancEQVring a diriglblo. 65, 70-7E, 7W 

Mai^y, de, 278 

~ dm. Sir Uinm, 213 ■ 



ainliip, 82. SS. S4, SSC M 
Hllitaiy apptknini, l«aL 9B»-»I.S9 
Monaco, PrioMcC 10t» 151, SSL S7 
Monocjcle; w|ilw aC Wi%ht 

Fiftfw. 1^ «i»M,n ML an 

IffonopSuie, 139 

aUenms, 144. 14C 307. 20. 2S 

Antoinette. Hi. n»-SS 

Blefiot. 141. 906-211. 23S. SO, SI, 

252. 253. 2M 
chunt, 211. 219. 223 
control. 206,212 
Bnaalt-Feltcrie. 141. 213-219 
Gastamfaido, 141, 220 
8aatos-D«moBl» 14U 230 
Tatin, 225-228 




praptDkif teetw 

d'AnJcoait, 119. 212 

of peae uaU oa. 157-159. 220 
to U cffoctad. 113-115, 279 
FropeOcEi. 09-«^ iM, S4. 8S. 193-119*- 
168. 190t 19S, Sfl^. 293, 210.2i3» St^^- 

wing.warpiag. 145^ 194, 19ft. 196, 202. 
MontgoUler, 13, 82 
^Mooring" aRaogemnt for dfriglblea» 

Hoton, 159-162. 198 

Antoinette, 160, 190, 210, 223, 224 


Clement, 228 

Cl^eot-Bayard (Tatin). 227, 228 

Electrical, 89, 92 

Bsnaolt-Ptiterie, l«K 212. 214. 215,218. 

explosion, 10, 94 

hnman. 8, 84 

Mercedes, 98 

Renault, 160, 203 

rotary, 161 

steam, weight of, 8-9 

Nadab. 242 

OBinTHOPT^n. 120, 182, 238, 289 

Adh. de la Hanlt, 182, 238 

American. 239 
Orthogonal system, 138 
Osiris Prize, 252, 277 

PAiNLXvi, 280, 281, 232, 233, 255 
Parsend, von, 108 
military airship, 108 


P^jloii. laaacbiag (WifgM)* 1^ ^^ 201 
QuAUTT. sastamtwg. 133, 137, 138 

«* Radius of actMm,** 
somplsnoB. 281 

aiiBbips, 21-23, 270. 271. 275, 276, 290 
fiaU. Wr^ht Uoncbing, 154, 196. 201 
Renard. Colonel, 7, 9, 11, 17. 37, 38, 39» 
44. 48, 49, 60, 67, 90-94, 115, 137, 
163. 167, 180. 182. 195, 235, 248, 286 
Commander Paol. 90. 143 
Renaalt. 160-203 
R^tMifme. la, 67, 99, 100, 112, 113, 

Resistance of the air, 14. 126, 129 
Reme, airienne, la, 256 

de I'aviation, 256 
Ricaldoni, Captain, 108 

Rigid halloons, 28, 104-108 
etefating of aeroplanes, 151, 189, 195, 
203, 205. 212, 217, 218. 222. 927. 
of ainOiips, 29-31 
steering of airships, 29-31, 64 
of aeroplanes, 150. 151, 188, 195-198, 
202, 205, 208, 217, 222, 237, 329 

Savitt, airship, 61, 79-81 

aeroplane. 173-178 
SantOB-Dnmont, 20, 95-96, 113, 141» 

280, 249, 250 

S94 im 

BoMW* (M Piop«Ucn). 
MTOplane, 163-166. ISO. IBS, 208, 210. 

•m, S2B, 236, 237, 238 
dimeiuloiii. 67, 6S, S9. 92. 98. 103. 

DDinbeiof. iea,lS4. ISG 
pitob. 66, 67, 92, 192. 164 
poailion of, 41-44. 68, H S8, 103, 

■Up.66,67. 69, 162 
■peed. 67. 68, 611, 92. 102, 104, 113, 162, 

■DBtalnlDg. IKO, 181, 23S-237 
SmIIod, tnniveiBe ol wiDgi. Ii7, 1GS> 

>Je1fridge, Ueutenant, 164, 198, 24S 
BeTeto d'Albaqnerqae, 96 
Shape, IcltuenQe of front, H-t6 

Btem, 16 
Sboroi. Utiding. 223. 221 
fikaCes, laodiDg, 194 
Sociute fcEUi^BiBe de navlgatkiii a£rieiia«, 

122, 2S5 
SOTUD, 122. ISG. 168, 174, 176, 246.!fiG, 

286, 2S7 
Speed, critical, 38-49 

aeroplane, 1S9, 170. 171 

indepeodent of airships, 49-G4, 69, 67' 
93, 113, 114 

regulating, of aeroplacies. 126, 17l~ 
Bpread— <(( Aeroplanes 

aeroplane automatic, 116. H7. 118, 

artificial, 149 
Stabilisator, 64, 65, 66 

direction, 33-7, U^IGO 

height, se, 30 

loDgitadinal, 33-S7, 111 

transTerse, 141 
Snrooof, 14, 71-76. 97, 100, 102 
Sarfaces, aopportiog, 126, 127, 167 

■lUtaJDiog, 124, 13T-I3S 
BOBpenslans, parallel (delormable), 62 

triangular (icdeformable}, G2 
tjostectatioa, 124 

capacitiei, 137-13S 

Tabls of wind speeds micimd Pari*, SS 
TatiD, 100,226.226 

aeroplane, 225, 226, 227. 228 
Thrail. centre of. 130 
TUHodier, 17, J4, 89 
Tibs sport, aerial, 257, 258. 3S9. 36S, 361, 

265, 266 

VAOA.BtEB of atmosphere, 122, ITS. 171, 

Valve, 61 

Bippjng, 61 
Vauli, Cowit de la, 13, 7». 80. 103 
Tendfime. aeroplane, 226. 228, 229. 230 
ViUt-de-BoTiUatix. 102 

■Parii, 10, 41, 67. 100-103, IBS, 260, 
Voisin, 167, 168. 187-192. 226, 230, 231, 

232, 249, 253 
Voyages : 

Bayard- Cltmml, 76,77, 2G4 

BUrlot, 301. 212, 213, 260, 2G1. 2G2 
263, 264 

Fannaii, Henri, 190. 233, 260, 261 

Franct, la, 93. 94 

Latham, 224, 226. 2G1 BS 

JUpvUiifiit, 100 

SarUoi-Dviaont, B6, 96, 230, 219, 250 


Wright Brothers, 247, 265 

2tpfilin, 100, 107, 108 

Weight lannchiDg, 151, 198. 201 
Welfetinger, 221 
Weabam. 212 
Wind, 46 

ascending, 173-78 

dtscendiog, 173-78 

direction, 46 

preaaore, 15-47 

relaUw, 47-52. 170-72 

table of speeds, 66 
velocity. 46-47, 56-58 
Wings, birds. 121 
constmctioD , I3S-37 
ipread — «e Aeroplane 


ot,H6.1». l0G.lSS.2O2.aifl. 
Wright Brotben. 137, 141. 14S, 140| 161, 
108, 164, ISa. 167, 102-201, 203. 219, 
22G. 230-34, 342, 341, 245, 248. 247. 


TAOHTS,aaia), 77. 78. 79 

Zahaboff. 282 
Z«ppellii, Coont, lOS 

Unblp*, 20, 2B, 78. 104-8, 370 
ZIpM, 102 
jbdiaaainhip, 77, 78, 79